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 Issued October 9, 1912. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 158. 
 
 A. D. M ELY IN, CHIEF OF BUREAU. 
 
 ;HE ROUNDWORMS OF DOMESTIC SWINE, 
 
 WITH SPECIAL REFERENCE TO TWO SPECIES 
 PARASITIC IN THE STOMACH. 
 
 BY 
 
 WINTHROP D. FOSTER, 
 
 Junior Zoologist, Zoological Division. 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1912.
 
 Bui. 168, Bureau of Animal Industry, U. S. Dept of Agriculture. 
 
 PLATE I. 
 
 Hainas.del __ 
 
 A PORTION OF THE PYLORIC END OF A HOG'S STOMACH. INFESTED WITH 
 AROUENNA STRONQYLINA AND PHYSOCEPHALUS SEXALATUS. (NATURAL SIZE.) 
 
 The worms appear as fine red lines partly buried in a yellow glairy mass of necrotic tissue. 
 Ulcers are found underneath this necrotic tissue.
 
 Ksm-.l ( X-II.I..T 9, 1912. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 158. 
 
 A. D. MELVIN, CHIEF OF BUREAU. 
 
 THE ROUNDWORMS OF DOMESTIC SWINE, 
 
 WITH SPECIAL REFERENCE TO TWO SPECIES 
 PARASITIC IN THE STOMACH. 
 
 BY 
 
 WINTHROP D. FOSTER, 
 
 Junior Zoologist, Zoological Division. 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1912.
 
 BUREAU OF ANIMAL INDUSTRY. 
 
 Chief: A. D. MELVIN. 
 
 Assistant Chief: A. M. FARRINGTON. 
 
 Chief Clerk: CHARLES C. CARROLL. 
 
 Animal Husbandry Division: GEORGE M. ROMMEL, chief. 
 
 Biochemic Division: M. DORSET, chief. 
 
 Dairy Division: B. H. RAWL, chief. 
 
 Field Inspection Division: R. A. RAMSAY, chief. 
 
 Meat Inspection Division: RICE P. STEDDOM, chief. 
 
 Pathological Division: JOHN R. MOHLER, chief. 
 
 Quarantine Division: RICHARD W. HICKMAN, chief. 
 
 Zoological Division: B. H. RANSOM, chief. 
 
 Experiment Station: E. C. SCHROEDER, superintendent. 
 
 Editor: JAMES M. PICKENS. 
 
 ZOOLOGICAL DIVISION. 
 
 Chief: B. H. RANSOM. 
 
 Assistant zoologists: ALBERT HASSALL, HARRY W. GRAYBILL, MAURICE C. HALL, and 
 
 HOWARD CRAWLEY. 
 Junior zoologist: WINTHROP D. FOSTER. 
 
 2
 
 LETTER OF TRANSMITTAL. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY, 
 
 Washington, D. C., July 2, 1912. 
 
 SIR: I have the honor to transmit herewith a manuscript entitled 
 "The Roundworms of Domestic Swine, with Special Reference to 
 Two Species Parasitic hi the Stomach," by Mr. W. D. Foster, of the 
 Zoological Division of this bureau. I respectfully recommend its 
 publication in the bulletin series of the bureau. 
 
 The paper deals particularly with two species of nematodes which 
 have recently attracted considerable attention in connection with 
 the Federal meat inspection. The parasites are shown to be of wide 
 distribution and frequency of occurrence hi American swine, and they 
 are a source of possible serious injury to these animals. 
 
 The illustrations were drawn by Mr. W. S. D. Haines, of this 
 bureau. 
 
 Respectfully, 
 
 A. D. MELVIN, 
 
 Chief of Bureau. 
 Hon. JAMES WILSON, 
 
 Secretary of Agriculture. 
 
 3
 
 CONTENTS. 
 
 Page. 
 
 Summary 7 
 
 Introduction 8 
 
 Family Filariidse 9 
 
 Subfamily Arduenninac 9 
 
 Genus Arduenna 9 
 
 Arduenna slrongylina 10 
 
 Arduenna dentata 20 
 
 Genua Physocephalus 21 
 
 Physocephalus sexalatus 21 
 
 Comparison of Physocephalus sexalatus and Arduenna strongylina 31 
 
 Other species referred to Physocephalus sexalatus 31 
 
 Distribution of Arduenna strongylina and Physocephalus sexalatus in the United 
 
 States , 32 
 
 Relative frequency of the two species 34 
 
 Lesions associated with Arduenna strongylina, Arduenna dentata, and Physo- 
 cephalus sexalatus 34 
 
 Life history 3g 
 
 Preventive measures .' 37 
 
 Medicinal treatment 37 
 
 Key to the round worms parasitic in domestic swine 38 
 
 Classified list of the roundworms parasitic in domestic swine 41 
 
 Bibliography 45 
 
 5
 
 ILLUSTRATIONS. 
 
 PLATE. 
 
 PLATE I. A portion of the pyloric end of a hog's stomach, infested with Arduenna 
 
 strongylina and Physocephalus sexalatus Frontispiece 
 
 TEXT FIGURES. 
 
 Page. 
 
 FIG. 1. Arduenna strongylina. Median view of cephalic end 10 
 
 2. Arduenna strongylina. Burea of male, ventral view 11 
 
 3. Arduenna strongylina. Posterior end of body of male, viewed from right 
 
 side 12 
 
 4. Arduenna strongylina. Posterior end of body of female, viewed from 
 
 leftside 12 
 
 5. Arduenna strongylina. Ventral view of middle of body of female. ... 13 
 
 6. Arduenna strongylina. Lateral view of egg removed from a ruptured 
 
 uterus 13 
 
 7. Arduenna strongylina. Short spicule with retractor muscles, viewed 
 
 from right side 14 
 
 8. Arduenna strongylina. Posterior end of body of male, viewed from 
 
 leftside 14 
 
 9. Arduenna strongylina. Cross section through body of female in the 
 
 region of the vulva 15 
 
 10. Arduenna strongylina. General view of body of male from right side. 15 
 
 11. Arduenna strongylina. General view of body of female from left side . 16 
 
 12. Arduenna strongylina. Cephalic end 17 
 
 13. Arduenna strongylina. Bursa of male, ventral view 17 
 
 14. Physocephalus sexalatus. Lateral view of cephalic end 18 
 
 15. Physocephalus sexalatus. Lateral view of cephalic end 18 
 
 16. Arduenna dentata. Median view of cephalic end 20 
 
 17. Arduenna dentata. Bursa of male, ventral view 20 
 
 18. Physocephalus sexalatus. Dorsal view of anterior end of body 22 
 
 19. Physocephalus sexalatus. Posterior end of body of male 23 
 
 20. Physocephalus sexalatus. Bursa of male, viewed from left side 24 
 
 21. Physocephalus sexalatus. Posterior end of body of female, ventral 
 
 view 25 
 
 22. Physocephalus sexalatus. Ventral view of body of female in the region 
 
 of the vulva 25 
 
 23. Physocephalus sexalatus. Lateral view of egg removed from a ruptured 
 
 uterus 26 
 
 24. Physocephalus sexalatus. Bursa of male, ventral view 26 
 
 25. Physocephalus sexalatus. Cross section through anterior part of body. . 27 
 
 26. Physocephalus sexalatus. Ventral view of body of female 27 
 
 27. Physocephalus sexalatus. Lateral view of anterior end of body 28 
 
 28. Physocephalus sexalatus. General view of body of male 29
 
 THE ROUNDWORMS OF DOMESTIC SWINE, WITH SPECIAL REF- 
 ERENCE TO TWO SPECIES PARASITIC IN THE STOMACH. 
 
 SUMMARY. 
 
 Two species of roundworms belonging to the family Filariidse, of particular interest 
 to helminthologists and veterinarians on account of their wide distribution and fre- 
 quency of occurrence in American swine and the possibility that they may cause 
 serious injury to their host, are given special consideration in this paper. 
 
 One of these species, identified as Spiroptera strongylina, has recently been placed 
 in a new genus, Arduenna, of which it is the type, and several errors regarding the 
 anatomy of this parasite have been corrected. Another species, Arduenna dentata, 
 has been found in China associated with Arduenna strongylina, and although not yet 
 reported in American swine is mentioned in this connection, as further investigation 
 may reveal its presence in this country. 
 
 Arduenna strongylina is much more common in American swine than it is said to 
 be in European swine, and has been found abundantly in the slaughterhouses at St. 
 Louis, Chicago, South Omaha, and Kansas City, and has also been collected at Ben- 
 ning, D. C., and Bethesda, Md. 
 
 Specimens of hogs' stomachs received from Chicago showed the worms deeply 
 fastened in' the submucosa or embedded in necrotic tissue near which were deep 
 ulcers. The condition suggested infection with Bacillus necrophorus, the inoculation 
 of which might easily result from the burrowing of the worms; however, owing to the 
 sterile condition of the specimens received, this could not be satisfactorily demon- 
 strated. A similar diseased condition of the stomachs of hogs in Europe is attributed 
 by Von Ratz (1899d)' to infection with Arduenna strongylina. Under the circum- 
 stances the worm should be regarded with grave suspicion, and general prophylactic 
 measures for the prevention of the spread of infection are suggested. 
 
 Commonly associated with Arduenna strongylina in this country is another worm, 
 identified as Physocephalus sexalatus, first described by Molin (1860b) from specimens 
 from the peccary (Dicotyles labiatus) from Brazil; also found by him associated with 
 Arduenna strongylina from the wild boar in Germany. It is also reported by Von 
 Linstow (1879b) (who apparently mistook this species for Arduenna strongylina) 
 and Piana (1897e), from Europe, and by Railliet and- Henry (1911b), from Madagascar 
 and Indo-China, in the former case associated with a severe gastritis. Seurat (1912) 
 has recently reported this species from the ass and dromedary in Algeria, but his 
 statements would seem to require confirmation. 
 
 According to the writer's experience, Physocephalus sexalatus is almost as widely 
 distributed as Arduenna strongylina, since out of eight lots of specimens of the latter 
 species, specimens of Physocephalus sexalatus were found in all but one. In a mixed 
 infection, however, it has never been found as abundantly as Arduenna strongylina. 
 This worm has apparently the same habit of injuring the mucosa as has Arduenna 
 strongylina, as both species were found in the same necrotic tissue in a hog's stomach. 
 It must therefore be considered only less dangerous because it is less abundant, and 
 should be subject to the same treatment suggested for infestation with Arduenna 
 strongylina. 
 
 ' References to literature will be found in bibliography at end of bulletin.
 
 8 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 Nothing is known in regard to the life cycle of these parasites, but their wide distri- 
 bution and frequency of occurrence suggest a simple life history without an interme- 
 diate host. The fact that the eggshells of both species are relatively thick would 
 seem to indicate that the embryos are not liberated until the shell is dissolved by the 
 gastric juice of the host. From the fact that the embryos are fairly well developed 
 before oviposition, it may be inferred that the eggs require but a short period of incu- 
 bation. 
 
 Following the discussion of the two species is a key for use in the identification of 
 round worms parasitic in swine; also a list of these parasites classified according to their 
 zoological position. 
 
 INTRODUCTION. 
 
 Nematodes occurring in the stomach are commonly present among 
 swine in the United States. These have usually been considered by 
 veterinarians, pathologists, and others who have had occasion to 
 mention them as belonging to the species Spiroptera strongylina 
 Rudolphi, 1819, although some have expressed a doubt as to the cor- 
 rectness of the identification. In addition to the forms which have 
 been identified as Spiroptera strongylina, Hassall and Stiles (1892a) 
 have described a species named by them Strongylus rubidus, and 
 which has since been collected from domestic swine in Europe. 
 
 Recently a zoological study of specimens of nematodes in the hel- 
 minthological collection of the Bureau of Animal Industry, collected 
 from the stomachs of hogs in various parts of the United States, was 
 undertaken by the present writer, largely as a result of reports from 
 inspectors relative to the prevalence of nematodes in the stomachs 
 of swine, Drs. J. J. Brougham and T. B. Pote, of the St. Louis station, 
 having been among the first in the Federal service to give attention to 
 the subject from the standpoint of meat inspection. As a result of this 
 study and of a comparison of these specimens with specimens of 
 Spiroptera strongylina received from Europe, the conclusion has been 
 reached that in several particulars the descriptions of Spiroptera 
 strongylina commonly given by European writers are in error, and 
 that the forms commonly identified as Spiroptera strongylina represent 
 two distinct species, one of them Spiroptera strongylina, the other cor- 
 responding to Physocephalus sexalatus (Molin, 1860) Diesing, 1861, 
 hitherto considered a rare parasite and until recently reported only 
 once for domestic swine. 
 
 According to Stiles and Hassall (1905b), the genus Spiroptera is 
 preempted by the genus Acuaria Bremser, 1811, whose type is 
 anthuris. This species is also the type of Dispharagus Dujardin, 1845, 
 a genus based largely on certain nematodes of birds and not found in 
 mammals. According to this ruling, the genus Acuaria is confined to 
 certain parasites of birds and fishes characterized by a differentiation 
 in the structure of the esophagus. As Spiroptera strongylina does 
 not conform to the type of Acuaria or the characteristics of the genus, 
 a new genus to include these forms is necessary. This deficiency has
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 9 
 
 been supplied by the creation of a new genus, Arduenna, by Railliet 
 and Henry (1911), Spiroptera strongylina being taken as the type. 
 Both Arduenna and PJiysocephalus, together with Simondsia paradoxa, 
 belong in the family Filariidse, 1 and are included by Railliet and 
 Henry (191 Ib) in the new subfamily Arduenninae. 
 
 FAMILY FILARIIDSE, GLAUS, 1885. 
 
 FAMILY DIAGNOSIS. Nematoda: Body long, filiform. Mouth surrounded with 
 papillae, or provided with two lips. Esophagus slender, without posterior bulb. 
 Males with a single spicule or with two unequal spicules. Females with two ovaries; 
 vulva usually in front of the middle of the body. Usually ovoviviparous. Develop- 
 ment in many cases requires an intermediate host. 
 
 TYPE GENUS. Filaria Muller, 1787. 
 
 Subftmaily AJIDTJENNIN^E Railliet tmd Henry, 1911. 
 
 SUBFAMILY DIAGNOSIS. Filariidae: Mouth with two lateral lips leading into a 
 pharynx marked with cuticular ridges in the form of spirals or rings. Spicules 
 unequal, the longer several times the length of the shorter. Four pairs of preanal 
 papillae. Eggs containing embryos when oviposited. 
 
 TYPE GENUS. Arduenna Railliet and Henry, 1911. 
 
 Genus ARDUENNA Railliet and Henry, 1911. 
 
 GENERIC DIAGNOSIS. Filariidee: Body subcylindrical, attenuated anteriorly, 
 posteriorly somewhat broader, usually curved in a semicircle, marked by a narrow, 
 longitudinal cuticular wing on the left side, extending nearly the length of the body. 
 Cuticle densely striated transversely. Mouth with two lateral lips, each lip with 
 three lobes, leading into a small buccal capsule containing two lateral teeth, and fol- 
 lowed by a cylindrical pharynx marked with cuticular ridges forming a series of spirals. 
 Esophagus continuous, gradually broadening posteriorly and occupying from one- 
 fourth to one-third of the body length. Caudal end of the male curved in a single 
 turn. Bursa asymmetrical, the right bursal wing being broader than the left wing, 
 furnished with five pairs of stalked papillae asymmetrically arranged, of which one 
 pair is preanal, three pairs are adanal, and the fourth pair is postanal. Bursal mem- 
 brane marked with longitudinal and transverse striae, giving it a wrinkled appearance. 
 Anus surrounded by a cuticular thickening, serrated on the outside edge. Spicules 
 long and very unequal, the longer five to seven times the length of the shorter. Vulva 
 anterior of the middle of the body. Eggs with thick shells containing embryos at the 
 moment of oviposition. Parasitic in the stomachs of Suidse. 
 
 TYPE SPECIES: Arduenna strongylina (Rudolphi, 1819), Railliet and Henry, 1911. 
 
 Diesing (1861a) proposed the family name Spiruridea for a group of nematodes distinguished from 
 FUaria by the curl or spiral twist of the tail of the male. This family is not accepted by most recent writers 
 on the ground that it is not based on sufficiently characteristic morphological features, and that the name 
 does not conform to the rules of zoological nomenclature. Oerley(18S5a), Leiper (1908), and Railliet and 
 Henry (1911b) use the name Spiraridae, apparently modifying Diesing's (1861a) family name Spiruridea 
 to conform to the present zoological nomenclature. The family name Spiropterldae Is proposed by Leroer 
 (1911). 
 
 Owing, however, to the apparent invalidity of the name Spiroptera, the present writer prefers not to use 
 either the family name Spiruridse or Spiropteridse, and although it is evident that the genera Arduenna 
 and PJiysocephalus, and other genera as well, will ultimately be separated from the Filariidse, it is not con- 
 sidered desirable to attempt such a revision until a more careful study has been made of the various species 
 involved. In the present paper, therefore, A rduenna and Physoccphalus are retained in the family Filariidse 
 but included under the subfamily Arduenninse, Railliet and Henry, 1911. 
 
 52865 Bull. 15812 2
 
 10 
 
 THE BOUNDWORMS OF DOMESTIC SWINE. 
 
 Arduenna strongylina (Rudolphi, 1819) Railliet and Henry, 1911. 
 
 1819: Spiroptera strongylina Rudolphi, 1819a, p. 23. 
 
 1819: Spiropteru strongylina Rudolphi, 1819a, p. 237. Misprint for 
 
 Spiroptera. 
 
 1828: Spiroptera strongyliformis De Blainville, 1828a, p. 546. 
 1866: FUaria strongylina (Rudolphi) Schneider, 1866a, p. 101. 
 
 /fomm. 
 
 FIG. 1. Arduenna strongylina. Median view of cephalic end. b. c., buccal capsule; cut., cuticle; <., 
 esophagus; lab. p., labial papillae; ph., pharynx; t. b. c., teeth of the buccal capsule. X 560. (Original.) 
 
 SPECIFIC DIAGNOSIS. Cuticule densely striated transversely, increasing in thickness 
 toward the anterior extremity, which is furnished with two cervical papillae placed 
 asymmetrically, the left being about 190 p and the right 390 fi from the anterior ex- 
 tremity. Beginning at a point 280 fi from the anterior end on the left side, a narrow 
 cuticular wing gradually increasing to a maximum breadth of 35 p. extends to a point 
 about 2 mm. from the posterior extremity. Mouth 44 to 45 ft in diameter with two 
 lateral lips each with three lobee, having a small round papilla at the base of each of 
 the lobes. Just below the lips and projecting into the mouth cavity are two chitinous 
 teeth, formed by a prolongation of, the wall <?f. the pharynx (fig. 1). The pharynx, 29 /*
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 11 
 
 wide by 83 to 98 p long, is marked on the inside by a series of chitinous ridges in the 
 form of continuous spirals (or a multiple spiral), all running in the same direction and 
 appearing like the threads of a quadruple screw. 
 
 Esophagus 3.1 to 3.7 mm. long, or about one-fourth of the body length, and 117 to 
 127 ft wide at its widest part near the base. Nerve ring 0.35 mm. and excretory pore 
 0.48 mm. from the anterior end. 
 
 Male 10 to 15 mm. long, averages about 13 mm. in length; 301 to 387 p wide at the 
 widest part just above the bursa. The bursal wings extend from a point about 1.2 
 mm. from the caudal extremity to the tip, the body ending in a blunt point. Bursal 
 wings irregularly ovate, ^^^^^^^.^ 
 
 asymmetrical, the right bur- 
 sal wing being about twice 
 as wide as the left wing. 
 The bursa contains 5 pairs 
 of stalked papillae asym- 
 metrically arranged, of 
 which 4 pairs are preanal 
 and the last pair is post- 
 anal. Bursa marked with 
 fine longitudinal striae, in- 
 creasing in density toward 
 its base (fig. 2). Spicules 
 two, grooved on the ven- 
 tral surface, the left spicule 
 2.24 to 2.95 mm. long, 
 very slender, ending in a 
 fine point and presenting 
 a slightly concave sur- 
 face near the tip on the 
 dorsal side. The right 
 spicule (about one-fifth of 
 the length of the left spicule) 
 is stouter and blunter at the 
 point, measuring 10 [i at its Jr / 
 
 base, or nearly twice the jr 10fTim. 
 
 width of the base of the 
 long spicule, and is 457 to 
 619 (i long (fig. 3). Anus 
 155 to 200 ft from the pos- 
 terior end and surrounded 
 on the posterior and left side 
 by a cuticular thickening 
 (circumanal ring), the outer 
 edge of which is serrated. 
 
 Female 16 to 22 mm. long, 
 263 to 420/i wide; average maximum width 368 p, at a point about one-third of the 
 distance from the head to the caudal end. For the next third of the distance the 
 width remains constant except for a slight constriction in the region of the vulva. 
 Beginning at a point about two-thirds of the distance from the head to the caudal 
 end, where one of the uteri turns back on itself, the width gradually diminishes and 
 then abruptly decreases a short distance in front of the anus. Anus 215 to 275 p 
 from the caudal tip (fig. 4). 
 
 The orbicular naked vulva opening near the left side close to the lateral cuticular 
 wing is slightly anterior of the middle of the body, dividing the worm anteriorly and 
 posteriorly in the ratio 5 : 6. Vagina uniform, about 49 p in diameter, 1.7 mm. long, 
 
 FIG. 2. Arducnna strongylina. Bursa of male, ventral view, cl., 
 cloaca; l.b.w., left bursal wing; I. sp., long spicule; po. p., post- 
 anal papillae; pr. p., preanal papillae; r. b. w., right bursal wing; 
 . sp., short spicule; v. r. c., ventral ridge of the cuticle. X75. 
 (Original.)
 
 12 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 extending in a generally posterior direction, joining the uteri at a point about 1.1 mm. 
 from the vulva measured in a straight line (fig. 5;. 
 
 Eggs oval, 34 to 39 /i long by 20 ft wide, with thick shells. Embryos well developed 
 in the shell before oviposition (fig. 6). 
 
 HOSTS. Domestic hog (Sus scrofa domestica), wild boar (Sus scrofafera). 
 
 LOCATION. Stomach and small intestine. 
 
 LOCALITIES COLLECTED. United States: Bethesda, Md.; Benning, D. C.; Chicago, 
 111.; South Omaha, Nebr.; St. Louis, Mo.; Kansas City, Mo.; Denver, Colo.; Brazoa 
 
 Lsa :_=. 
 
 Homm. 
 
 FIG. 3. Arduenna strongylina. Posterior end of 
 body of male, viewed from right side. I. sp. , long 
 spicule; s. sp., short spicule. X 65. (Original.) 
 
 County, Tex. Europe: Germany, 
 France, Hungary, Roumania, Italy. 
 Asia: Turkestan, Indo-China. 
 
 The number of spiral ridges 
 in the pharynx seems to vary 
 both with the sex and among 
 different individuals of the same 
 sex. In the specimen figured, a 
 
 Ho mm. 
 
 FIG. 4. Arduenna strongylina. Posterior end of 
 body of female, viewed from left side. a. , anus; 
 ov., ovary; p. ut., posterior uterus; red., rectum; 
 ter. p., terminal papilla. X 150. (Original.) 
 
 female (fig. 1), there are four separate ridges, the usual number for 
 females. Males have, as a rule, but three spirals. Kailliet and Henry 
 (191 Ib) mention 2 to 3 spiral ridges for males and 4 to 5 for females. 
 The retractor muscles controlling the movements of the right 
 spicule are a pair of narrow lamellar strips, longitudinally finely 
 striated, asymmetrically twisted in the center, attached at the pos- 
 terior end to the spicule and at the anterior end to the ventral side
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 13 
 
 //7/1 
 
 of the body. The muscles are fullv as long as the spicule they control 
 (fig. 7). 
 
 The vas deferens appears as a tube of darker color than the intes- 
 tine, about 130 fjL in its average diameter, and extending throughout 
 the posterior third of the body length. About 450 p from its ter- 
 minus it rapidly diminishes in diameter toward the cloaca, and in 
 the specimen figured (fig. 8) is bent in 
 the shape of the letter S. The seminal 
 tube is very long and convoluted, re- 
 sembling in appearance the ovaries of 
 the female. Near the posterior end of 
 the male the intestine, 123 // wide, first 
 crosses above the vas deferens toward 
 the dorsum, then curves underneath as 
 it approaches the cloaca. Its terminus 
 was obscured by the organs lying above 
 it. In the specimen figured (fig. 8) the 
 sheath of the right spicule is much con- 
 tracted and appears as a dark-colored 
 bag too short to contain the entire 
 spicule and within which the base of 
 
 the spicule 
 
 may be 
 
 dimly 
 
 seen. The 
 
 ventral 
 
 surface of 
 
 the male 
 
 -in the re- 
 gion im- 
 mediately 
 
 anterior of 
 
 the bursa 
 
 is f u r - 
 
 nished with 7 to 8 parallel longitudinal 
 
 , , cuticular ridges divided transversely 
 
 IQjuL. into serrations. This structure, modi- 
 
 FIQ. 6,Arduenna strongylina. Lateral fications of which are seen in many 
 
 view of egg removed from a ruptured ne matodes. including PTimOCephdluS 
 uterus, o. c., albuminous covering; . . 
 
 emb., embryo; sh., sheii. x 1,450. sexalatiLS, probably assists in maintain- 
 ing the position of the male in copula- 
 tion, as suggested by Ciurea (1911). The anus is partially encircled 
 by a rim of thickened cuticle, the outer edge of which is ornamented 
 with serrated cuticular projections. This cuticular thickening 
 extends along the posterior and left sides of the anus, forming about 
 
 6. 
 
 FIG. 5. Arduenna strongylina. Ventral 
 view of middle of body of female, a. tit., 
 anterior uterus; int., intestine; j. ut., 
 junction of the uteri; I. c. w.', lateral 
 cuticular wing; p. ut., posterior uterus; 
 v. vulva; va., vagina. X 58. (Original.)
 
 14 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 two-thirds of a complete circle. The thickened cuticle seems to 
 
 project downward into the body (fig. 2). 
 
 Ciurea (1911) depicts 10 tactile papillae located on the ventral 
 
 surface of the body of the male, close to the tip of the tail. These 
 
 could not be seen in the specimens studied 
 by the writer. The rectum (fig. 4) of the 
 female is about 80 /z in maximum width and 
 nearly as long as the distance from the anus 
 to the tip of the tail. In the region immedi- 
 ately posterior of the anus several fine lines 
 
 FIG. 7. Ar due nna strongylina. 
 Short spicule with retractor 
 muscles viewed from right side. 
 ret. m., retractor muscles; *. sp., 
 short spicule. X 80. (Original.) 
 
 can be seen beneath the 
 cuticle, converging toward 
 the base of the anus. These 
 are probably muscle fibers 
 controlling the rectum, and 
 are seen in the females of 
 many nematodes. A pair 
 of papillae close to the tip 
 of the tail extend laterally 
 to the edges of the caudal 
 cuticle on the ventral 
 side. 
 
 In a cross section of Ar- 
 duenna strongylina (fig. 9 of 
 the present article) , Ciurea 
 (1911) shows that the in- 
 terior of the lateral wing 
 is filled with a substance 
 shaped like the letter V 
 when viewed in this posi- 
 tion. In its reaction to 
 hematoxylin it resembles the thickened wall of the pharynx. 
 
 The same drawing (fig. 9) also shows that the vagina first passes 
 between the cuticle and muscular wall as it crosses the body to ex- 
 tend along the right side. In several of the specimens examined by 
 him, Ciurea (1911) noticed a drop of hardened cement at the opening 
 
 Ho mm. 
 
 FIG. 8. Arduenna stroru/yUna. Posterior end of body of 
 male, viewed from left side, cl., cloaca; int., intestine; 
 I. b. w., left bursal wing; po. p., postanal papillae; pr. p., 
 preanal papillae; pr. r. , perianal ring; sh. I. sp. , sheath of long 
 spicule; sh. s. sp., sheath of short spicule; . sp., short spi- 
 cule; v. def., vas deferens; v. r. c., ventral ridge of the cuticle, 
 X 58. (Original.)
 
 THE ROUNDWORMS OP DOMESTIC SWINE. 
 
 15 
 
 FIG. 9. Arduenna ttrongylina. Cross section 
 through body of female in the region of the 
 vulva. bd. w., body wall; cut., cuticle; ., 
 eggs; int., intestine; tit., uterus; v., vulva; 
 va., vagina. Enlarged. ( After Ciurea, 1911. 
 Text fig. 1, p. 131.) 
 
 of the vulva, and in cross section it was seen that the same material 
 
 filled the terminus of the vagina. This material was not seen in 
 
 any of the specimens examined by the present writer. 1 
 
 The vagina (fig. 5) extends first transversely under the uteri and 
 
 intestine; then leading above these organs it continues posteriorly 
 
 and parallel with the intestine (except 
 
 for an S-shaped bend near its middle) 
 
 along the right side until it reaches 
 
 the junction of the uteri. 
 
 One of the uteri, commencing at the 
 
 end of the vagina, extends posteriorly 
 
 and dorsally without convolutions 
 
 (except for an S-shaped bend 875 // 
 
 from its vaginal end) until it reaches 
 
 a point 3.6 mm. from its union with 
 
 the vagina. 
 Here it makes 
 an abrupt 
 turn, runs 
 back anteri- 
 orly and ven- 
 trally, paral- 
 lel with its dorsal limb, until its outline is 
 lost to view beneath the mass of eggs distend- 
 ing both uteri and filling the body cavity 
 from the end of the esophagus to within a 
 short distance of the anus, greatly obscuring 
 the outlines of the organs. Throughout its 
 visible length this uterus is of nearly uniform 
 diameter, about 95 fi. The distal ends of the 
 two uteri are at opposite extremities of the 
 worm; the uterus that first extends poste- 
 riorly ends anteriorly at a point 613 fi anterior 
 of the base of the esophagus in a long con- 
 voluted ovary crowded into the narrow space 
 between the esophagus and the lateral mus- 
 cular wall. The other uterus, running in a 
 similar but reverse direction from the uterus 
 
 just described, turns first anteriorly for about 3.5 mm., then posteriorly, 
 
 ending at a point about 875 fj. from the tip of the tail. The diameter 
 
 of the posterior uterus, like that of the anterior uterus, is nearly 
 
 i Such a secretion is not, however, uncommon among nematodes. The writer has collected many speci- 
 mens of (Esophagostomum columbianum the vulva of which was closed by a plug of dark-red secretion 
 Insoluble in alcohol but which could easily be removed by a needle. Specimens of this parasite have been 
 observed so firmly welded in copulation that hot alcohol did not cause their separation and they yielded 
 only to forcible traction with a needle or forceps. 
 
 FIG. 10. Arduenna strongylina. 
 General view of body of male 
 from right side, b., bursa. X 7. 
 (Original.)
 
 16 
 
 THE ROUNDWORMS OF DOMESTIC SWINfi. 
 
 uniform, about 95 fi. The posterior ovary, much convoluted, fills 
 most of the space between the anus and the terminus of the posterior 
 uterus (fig. 4). The ovaries are long filiform tubes, 34 /j. in diameter 
 in their narrowest part. The thick-shelled eggs are covered with a 
 thin irregular membrane resembling the albuminous membrane of an 
 ascarid egg. Under high power a faint line at either pole can be 
 seen running transversely through the thickness of the shell, sug- 
 gesting an operculum. The embryo is surrounded by a thin envel- 
 ope, differentiated from the shell by its greater translucence and 
 lack of granulation (fig. 6). Most of the eggs in the uterus contain 
 well-developed embryos, but a few near the ovaries appear in the 
 
 morula stage. The shell, including 
 the translucent membrane surround- 
 ing the embryo, is 4 // thick, the 
 embryo occupying a space 11 // by 
 24//. 
 
 The general appearance of the two 
 sexes is represented in figures 10 
 and 11. 
 
 The first specimens of Arduenna 
 strongylina were collected by Bremser 
 and figured by him in his Icones 
 Helminthum (Bremser 1824c). They 
 were first described, however, by 
 Rudolphi (1819a, p. 237). His de- 
 scription may be freely translated as 
 follows.: 
 
 Head slender, continuous, mouth orbicular, 
 body somewhat attenuated anteriorly, tail of 
 male coiled either in a single spiral or in a 
 spiral and a half. A broad wing extending 
 on either side of the tail. Spicule very long. 
 Apex of the tail very short, naked. Apex of 
 the tail of the female depressed, straight, 
 subacute. 
 
 In a preliminary note Rudolphi (1819a) gives the measurement of 
 the males as about 5 lines long (=10.6 mm.) and the females as 7 
 lines long ( = 14.9 mm.). 
 
 Gurlt (183 la) is the first on record to collect the worm from domes- 
 tic swine. His description of the anatomy of Spiroptera strongylina 
 follows Rudolphi's, but contains also the statement that the vulva 
 is situated a short distance in front of the anus. He describes the 
 mouth as smooth, without papillae. Subsequently (Gurlt, 1847a) he 
 added to his description a note on the anatomy of the pharynx, the 
 first reference to this structure, which he describes as banded by two 
 spiral muscles (a misinterpretation of the spiral chitinous ridges of 
 
 FIG. 11 .A rduenna strongylina. General view 
 of body of female from left side, a., anus; 
 ut., uterus; v., location of vulva. X 7.5. 
 (Original.)
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 17 
 
 . Arduenna strongy- 
 
 Cephalic end. m., 
 
 mouth; ph., pharynx. 
 Enlarged. (After ourit, 
 
 1847a, PI. I, fig. 8.) 
 
 the pharynx) running the length of the esophagus in opposite direc- 
 tions (fig. 12). 
 
 Molin (1860b) describes the vulva as situated posteriorly, and 
 gives the following measurements: Males, 11 to 15 mm; females, 15 
 to 23 mm, which figures agree closely with the writer's measurements 
 of Arduenna strongylina. 
 
 Schneider (1866a) reexamining Rudolphi's ma- 
 terial, gives a correct drawing of the bursa of 
 Arduenna strongylina, showing 5 pairs of papillae, / 
 of which one pair is postanal, and describes the / 
 anus as surrounded posteriorly by a crown of 
 serrated cuticular prominences (fig. 13). His 
 description, however, does not in all respects 
 agree with his drawing, as he states that there 
 are 6 pairs of papillae while the drawing shows 
 only 5 pairs. His description is also in error in 
 regard to the position of the vulva, which he TlG - ] 
 describes as directly in front of the anus. 
 
 Von Linstow (1879b) states that the two 
 spicules measure respectively 0.72 and 0.26 mm. 
 and that the mouth is surrounded with 6 round papillae curved for- 
 ward (fig. 14). His drawing shows the pharynx with a series of 
 parallel ridges instead of a spiral. A comparison of his drawing (fig. 
 14) with the anterior end of PJiysocephalus sexalatus (fig. 15) gives 
 rise to the suspicion that Von Linstow has mistaken this species for 
 Arduenna strongylina, an opinion first expressed by Railliet and 
 
 Henry (1911b). 
 
 Zuern (1882 a) is the first to men- 
 tion the narrow lateral wing, extend- 
 ing longitudinally along one side of 
 the body. He describes it, however, 
 as being in a median position. As 
 has been shown, it extends along the 
 left side only. 
 
 Stossich (1897b) states that the long 
 spicule is three times the length of the 
 short spicule, a ratio evidently derived 
 from Von Linstow's (1879b) meas- 
 urements. 
 
 At a meeting of the Helminthological Society of Washington, the 
 
 writer (Foster, 1911) presented a note on Spiroptera strongylina in 
 
 which he pointed out the differences between the anatomical features 
 
 of specimens tentatively identified by him as Spiroptera strongylina 
 
 52865 Bull. 15812 3 
 
 FIG. 13. Arduenna strongylina. Bursa of 
 male, ventral view, cl., cloaca; po. p., 
 postanal papillae; pr. p., preanal papillae; 
 pr. r., perianal ring. Enlarged. (After 
 Schneider, 1866a, p. 101.)
 
 18 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 FIG. 14. PhysocephaliM sezalatus. Lateral view of 
 cephalicend. lab. p., labial papillae; ph., pharynx. 
 Enlarged. (After Von Linstow, 1879b, Pl.V, fig. 11.) 
 
 and the descriptions of this species by European observers. As no 
 European specimens were at hand with which to compare the speci- 
 mens collected in this country, it was concluded either that the 
 
 American form represented a 
 distinct species or else the de- 
 scriptions of European writers 
 were in error in some important 
 details. In order to determine 
 which of the two alternatives 
 was correct, specimens collected 
 in the United States were for- 
 warded to Prof, von Linstow for 
 comparison with specimens col- 
 lected in Europe, and other 
 European helminthologists were 
 asked for specimens of Spirop- 
 tera slrongylina. The specimens sent to Von Linstow were considered 
 by him to be a different species from Spiroptera strongylina. There 
 is, however, no question that certain European specimens recently 
 received from Prof. Gedoelst, of Brussels, are specifically identical 
 with the American 
 form, nor can it be 
 doubted that the form 
 taken by Railliet and 
 Henry (191 Ib) as 
 Spiroptera strongylina 
 is the same as the 
 American form. 
 
 In regard to the 
 length of the spicules 
 of Arduenna strongy- 
 lina, the writer's ob- 
 servations are not in 
 accord with those of 
 Ciurea (1911). Meas- 
 urements of the spic- 
 ules of over 35 males 
 made with the aid of a 
 camera lucida and 
 stage micrometer 
 show that the long 
 spicule varies between2.24 and2.95 mm. in length, while the short spic- 
 ule is between 457 and 619 // in length. The corresponding measure- 
 ments given by Ciurea are, long spicule, 977 //; short spicule, 221 /t. 
 The measurements given by Railliet and Henry (191 Ib) are, long 
 
 iomm. 
 
 FIG. 15. PhysocepTialus sexalatus. Lateral view of cephalic end. cut., 
 cuticle; lab. p., labial papillae; ph., pharynx. X 415. (Original.)
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 19 
 
 spicule, 2.75 to 2.9 mm.; short spicule, 500 to 570 /z, thus confirming 
 the present writer's observations. 
 
 Arduenna strongylina, considered a rare parasite by Dujardin 
 (1845a), Neumann (1892a), and Railliet (1893a), is now known to 
 have a wide range. In this country at least it is very common, as 
 will be shown later. In Europe it has been collected from the wild 
 boar by Bremser (Rudolphi, 1819a) in Germany, and is reported by 
 Dujardin (1845a) in Austria, and by Railliet and Henry (191 Ib) in 
 prance from the same host. It has been reported for domestic swine 
 'in Germany (Gurlt, 183 la), Hungary (Von Ratz, 1899d), Italy 
 (Piana, 1897e), and Roumania (Ciurea, 1911). Most helmintholo- 
 gists, following the older writers, state that the parasite is rare and 
 occurs somewhat more commonly in the wild boar than in domestic 
 swine. Dujardin (1845a) states that "out of 19 wild boars dissected 
 at the museum of Vienna, only 2 had this worm in the stomach." In 
 Roumania, Ciurea found it in 9 out of 72 healthy swine, between 1 
 and 27 specimens being found in a single host. Outside of Europe it 
 has been reported by Von Linstow (1886c) from Turkestan, and by 
 Railliet and Henry (191 Ib) from Annam Province, Indo-China. 
 Some doubt, however, may be expressed regarding the identity of the 
 parasite reported by Von Linstow (1886c) since, as has been shown, 
 Von Linstow (1879b) has apparently confused PJiysocepTialus sexalatus 
 with Arduenna strongylina. The references to this parasite in the 
 United States will be considered in detail in another part of the paper. 
 Judging from its abundance in the United States, it seems not 
 improbable that a careful examination of hogs' stomachs in European 
 slaughterhouses would show, a more widespread infection than 
 hitherto reported. The specimens received by this bureau from 
 Gedoelst were unaccompanied with any data giving the host or 
 locality. Doubtless many veterinary schools and colleges throughout 
 Europe contain specimens both of this parasite and of PTiysocephalus 
 sexalatus which, like the specimens received from Gedoelst, have 
 never been reported in the literature. 
 
 An examination of the literature reveals only two authentic hosts 
 for Arduenna strongylina, namely, the European wild boar and 
 domestic swine, although most writers subsequent to Diesing (1851a) 
 have included the peccary in their lists of hosts. 
 
 Diesing (185 la) identified as Spiroptera strongylina some specimens 
 of worms in the Vienna museum collected by Natterer in Brazil, 
 April 24, 1826, from the stomach of the white-lipped peccary (Dico- 
 tyles labiatus) and labeled Spiroptera suis lalnati. As a result of his 
 identification he (Diesing, 1851a) added Dicotyles albirostris ( = Dico- 
 tyles Idbiatus Cuv.) 1 to the previously known hosts of Spiroptera 
 
 > Dr. H. W. Henshaw, Chief of the Bureau of Biological Survey of the United States Department of 
 Agriculture, in reply to a letter regarding the synonymy of Dicotyles labiatus, states (Feb. 24, 1911) that, 
 according to Dr. J. A. Allen, of his bureau, Dicotyles labiatus and albirostris are synonyms, labiatus having 
 preference as being the older term, the correct name, however, being Tayassu pecari Fischer.
 
 20 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 FIG. 16. Arduenna dentata. Median view 
 of cephalic end. ph., pharynx; t. b. c., 
 teeth of the buccal capsule. Enlarged. 
 (After Von Linstow, 1904f, PI. I, flg. 5.) 
 
 strongylina. The specimens were subsequently studied by Molin 
 (1860b), recognized as a new species, and named by him Spiroptera 
 sexalata. Later helminthologists, although accepting Molin's species, 
 have continued to include Dicotyles Idbiatus among the hosts reported 
 for Arduenna strongylina, apparently ignoring the fact that Molin's 
 (1860b) correction of Diesing's (1851a) identification eliminates the 
 
 peccary as a host of Arduenna stron- 
 gylina, since this, species has never 
 been reported in the peccary except by 
 Diesing (1851a). Stossich (1897b) ap- 
 parently considered Dicotyles albiro- 
 stris and D. labiatus as separate species, 
 listing under the former Spiroptera stron- 
 gylina and under the latter the para- 
 sites collected by Nattererfrom the pec- 
 cary and described by Molin (1860b). 
 The stomach appears to be the 
 normal location for Arduenna strongylina; Von Ratz (1899d), how- 
 ever, reports its occurrence in the small intestine. 
 
 Arduenna dentata (Von Linstow, 1904) Railliet and Henry, 1911. 
 Von Linstow's (1904f) description of this species is as follows: 
 
 Cuticula finely annulated. The mouth leads into a pharynx 0.11 mm. long. Ite 
 entrance is armed with a dorsal and a ventral tooth; the mouth is a transverse slit, the 
 border of which shows both an- 
 teriorly and posteriorly, three 
 notches with papillae (fig. 16). 
 
 1 ~ X./ I "\. \ 
 
 The esophagus measures -g-g of the \- 
 
 entire length and presents a spiral 
 musculature. In a young worm 
 14.6 mm. long, the nerve ring 
 surrounds the esophagus 2.64 mm. 
 from the head end, and the excre- 
 tory pore opens at a point situated 
 0.31 mm. behind it. The male 
 (25 mm. long by 0.79 mm. broad) 
 has a closely involuted tail which 
 resembles that of Spiroptera 
 strongylina. The spicules are re- 
 spectively 0.35 and 0.92 mm. long, 
 the shorter one bearing at its end 
 a barb. Immediately anterior of 
 the anus on each side there are four preanal papillae situated close together; behind 
 it there is one papilla. All have long stalks. The anus is surrounded by a broad 
 ring, notched externally; the bursa shows longitudinal rows of oval scales. (Fig. 17). 
 The female grows to a length of 55 mm. with a width of 1.10 mm. The short conical 
 tail is curved over the back; the vulva is placed far behind the middle and divides the 
 body in the ratio of 70 to 23. The eggs are small, thick shelled, and cylindrical, meas- 
 uring 0.039 by 0.017 mm. 
 
 FIG. 17. Arduenna dentata. Bursa of male, ventral view. 
 d., cloaca; I. b. w., left bursal wing; I. sp., long spicule; 
 po. p., postanal papillse; pr. p., preanal papillae; pr. r., 
 perianal ring. Enlarged. (After Von Linstow, 1904f, PL 
 I, fig. 7.)
 
 THE KOUNDWORMS OF DOMESTIC SWIXE. 21 
 
 The specimens described by Von Linstow were from the stomach 
 of Sus cristatus at Chilaw, Ceylon, and are deposited in the museum 
 of Colombo. Railliet and Henry (191 Ib) identify with Von Linstow's 
 (1904f) Spiropteradentata certain parasites collected from the stomachs 
 of pigs slaughtered at Hue", Annam Province, Indo-China, and include 
 them in the genus Arduenna. The specimens examined by Railliet 
 and Henry (191 Ib) differ, however, from Von Linstow's (1904f) de- 
 scription in the position of the vulva and the length of the spicules. 
 According to the former authorities, the position of the vulva is diffi- 
 cult to observe, but the spicules measure 3.75 to 4.23 mm., and 540 to 
 650 fj., respectively. 
 
 The principal differences between Arduenna dentata and Arduenna 
 strongylina are the greater size of the former and the fact that the 
 chitinous ring surrounding the cloacal opening, described for Arduenna 
 strongylina, forms an almost complete circle in the case of Arduenna 
 dentata, while in Arduenna strongylina it includes only the posterior 
 and left sides. Railliet and Henry's measurements for Arduenna 
 dentata are: Males: 25 to 35 mm. long by 700 to 800 //broad; females: 
 40 to 55 mm. long by 1.1 to 1.2 mm. broad. 
 
 Genus PHYSOCEPHALUS Diesing, 1861. 
 
 
 
 GENERIC DIAGNOSIS. Filariidse: Body elongated, subcylindrical, slightly tapering 
 anteriorly. Head marked off from the rest of the body by a cuticular inflation ending 
 abruptly in a circular line a short distance anterior of the posterior end of the pharynx. 
 Extending from the base of the cuticular inflation to about the middle of the body 
 are 6 lateral cuticular wings, 3 on each side, the middle wing of each 3 being broader 
 than the other two. Mouth with 2 trilobed lips, with a rounded papilla on each lobe, 
 and leading into an inconspicuous buccal capsule without teeth. Pharynx relatively 
 long and broad, marked by prominent ridges forming both spirals and simple rings, 
 and extending the length of the pharynx on the inside. Tail of the male twisted 
 spirally, furnished with a narrow symmetrical bursa supported by four pairs of preanal 
 papillae. Spicules long and unequal, the left spicule about five times the length of 
 the right spicule. Vulva somewhat posterior of the middle of the body; eggs smooth, 
 with thick shells, containing well-developed embryos at the moment of oviposition. 
 Endoparasitic in the stomach of suidae. 
 
 TYPE SPECIES. Physocephalus sexalatus (Molin, 1860) Diesing, 1861. 
 
 Physocephalus sexalatus (Molin, 1860) Diesing, 1861. 
 
 1860: Spiroptera sexalata Molin, 1860b, p. 957. 
 
 1860: Spiroptera strongylina suis labiati: Molin, 1860b, p. 957 
 
 (Museum label). 
 1861: Pfiysocepfialus sexalatus (Molin) Diesing, 1861 a, p. 686. 
 
 SPECIFIC DIAGNOSIS. Physocephalus: Head about 60 ji in diameter at the anterior 
 end, furnished with 2 tiilobed lips, each lobe being ornamented with a thick, rounded 
 chitinous papilla (fig. 15). The cuticle of the head, extending from the mouth to a 
 point 232 p from the anterior end, ia more or less inflated. Pharynx cylindrical, 263
 
 22 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 to 315 p long by 53 p wide, furnished with a spiral band which usually breaks up into 
 separate rings in the middle of its course and resumes the spiral toward the posterior 
 end. The number of turns to the spiral varies between 21 and 25. There is a cervical 
 papilla on the left side, 281 ft from the anterior end. The excretory pore opens on the 
 right side, 526 p from the anterior end. The lateral cuticular wings, 3 on each side, 
 commencing at the base of the cephalic cuticular inflation, extend posteriorly for a 
 distance about one-third of the body length. The middle wing of each three is 00 p 
 
 wide at its middle, the point of 
 greatest width. The other wings 
 are about half as wide (fig. 18). 
 
 Male, 6 to 9 mm. long, measured 
 in a straight line. Body nearly 
 uniform in diameter, averaging 
 263 ft, and attaining ite greatest 
 width of 315 p at the point of the 
 greatest width of the lateral 
 wings. The narrow bursal mem- 
 branes, about half the width of 
 the body, extend from a point 
 about 1.4 or 1.5 mm. from the 
 caudal extremity, to and includ- 
 ing the bluntly pointed tip (fig. 
 19). Caudal extremity twisted 
 into a fairly regular spiral, having 
 usually three turns. Long spicule 
 grooved on the ventral side, 2.1 
 to 2.25 mm. in length, or five to 
 six times the length of the short 
 spicule, very slender, gradually 
 tapering to a fine needle point. 
 Short spicule 300 to 350 p long, 
 relatively broad at its base, sud- 
 denly tapering to a fine point. 
 The ventral surface of the short 
 spicule is provided with a narrow 
 wing extending nearly to the tip. 
 Bursa furnished with eight pairs 
 of papillae (fig. 20). Of these the 
 four pairs of preanal papillae are 
 long and stalked; the postanal 
 papillae, close to the tip of the tail, 
 are very small, with short stalks. 
 Female 13 to 19 mm. long, 
 average about 16 or 17 mm. Maximum width 333 to 450 p in the region directly 
 anterior of the anus. The body rapidly increases in diameter from the anterior 
 end to the region of greatest width of the lateral cuticular wings. At this point 
 the diameter is nearly as great as in the region of the anus. It then rapidly 
 diminishes to half as much at the end of the first third of the body; then slowly 
 increasing, it reaches a maximum near the anus and abruptly diminishes, the 
 body ending in a blunt point furnished with a mucronate tip. Anus 120 p from the 
 caudal end, 50 p in diameter (fig. 21). Vulva posterior of the middle, 35 p in diam- 
 eter, dividing the body in the ratio of 9 to 8. The vagina extends posteriorly (fig. 22). 
 Uterus bilobed, the ovaries lying at opposite extremities. Eggs 34 by 15 ft, slightly 
 flattened at the poles. Embryo well developed before oviposition (fig. 23). 
 
 lo.mm. 
 
 FIG. 18. Physocephalus sexalatus. Dorsal view of anterior 
 end of body. c. cut. inf., cephalic cuticular inflation; c. p., 
 cervical papilla; ., esophagus; ex. p., excretory pore; lab. p., 
 labial papillae; I. c. to., lateral cuticular wings; n. r., nerve 
 ring; ph., pharynx. X 150. (Original.)
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 23 
 
 HOSTS. White-lipped peccary (Tayassu pecan), wild boar (Sus scrofa fera), 
 domestic hog (Sus scrofa domestica). 
 
 LOCATION. Stomach and small intestine. 
 
 LOCALITIES COLLECTED. Brazil; Italy; Germany; Roumania; Madagascar; Indo- 
 China; United States, east, middle, and southwest. (Apparently same range as 
 Arduenna strongylina.) 
 
 As already mentioned, Physoceph- 
 alus sexalatus was first identified 
 as Spiroptera strongylina by Diesing 
 (185 la). Molin (1860b) subse- 
 quently described the specimens 
 under the name Spiroptera sexalata, 
 and the following year Diesing 
 (186 la) placed the species in a new 
 genus Physocephalus, of which it is 
 the type and only species. The 
 specimens studied both by Molin 
 and Diesing were collected by Nat- 
 terer from the white-lipped peccary 
 in Brazil, April 24, 1826, and depos- 
 ited in the Vienna Museum labeled 
 Spiroptera strongylina suis labiati. 
 
 Molin's (1860b) somewhat meager 
 description sums up the salient 
 points (the lateral wings and spiral 
 tail of the male) by which Phy- 
 socephalus sexalatus may be recog- 
 nized. He describes the males as 
 7 mm. long and 2 mm. wide, and 
 the females as 9 to 13 mm. long and 
 3 to 5 mm. wide. The mouth is de- 
 scribed as bilobed, each lobe with a 
 three-cornered margin. Diesing 
 (1861a), although creating a new 
 genus from Molin's species, adds 
 little to our knowledge of its anat- 
 omy. 
 
 It has already been noted that 
 Von Linstow (1879b) has appar- 
 ently mistaken Physocephalus sexa- 
 latus for Arduenna strongylina. 
 His measurements of the spicules 
 (0.72 mm. for the long and 0.26 mm. for the short spicule) are, how- 
 ever, much too short for A. strongylina and also for P. sexalatus. 
 
 Von Drasche (1884a), in his reexamination of Diesing's and Molin's 
 specimens, made a careful study of the bursal papillae and the struc- 
 
 Momm. 
 
 c/. 
 
 FIG. 19. Physocephalus sexalatus. Posterior end 
 of body of male. 6. w., bursal wing; cl., cloaca; 
 1. *p.,long spicule; pr. p., preanal papillae; . 
 sp., short spicule; v. r. c., ventral ridge of the 
 cuticle. X 50. (Original.)
 
 24 
 
 THE ROUNDWORMS OP DOMESTIC SWIXE. 
 
 ture of the lateral wings, illustrating the description with drawings, 
 which were of great value to the present writer in verifying his iden- 
 tification. In common with Railliet and Henry (191 Ib) the present 
 writer was unable to find the pair of papillae depicted by Von Drasche 
 (1884a, fig. 24 of this article) close to the edge of the anus. Ciurea 
 (1912), however, depicts a pair of papillae immediately posterior of 
 the anus, which he states are not easily seen. At the extreme tip of 
 the tail Von Drasche (fig. 24) shows three pairs of minute apparently 
 sessile papillae. In reality there are four pairs of minute stalked 
 papillae at this point. These appeared very clearly with a high 
 
 ^lo mm, 
 
 FIG. 20.Physocephalus sexalatus. Bursa of male, viewed from left side, cl., cloaca; I. b. w., left bnrsal 
 wing; 1. sp., long spicule; po. p., postanal papillae; pr. p., preanal papillae; r. 6. w., right bnrsal wing; 
 sft. s.sp., sheath of short spicule; s.sp., short spicule; v. w., ventral wing of short spicule. X 100. (Orig- 
 inal.) 
 
 power in mounts presenting a somewhat lateral view (fig. 20). The 
 structure at the tip of the tail with its rows of minute papillae is not 
 unlike that depicted by Ciurea (1911) for the bursa of Arduenna 
 strongylina. As already stated, however, no such structure was seen 
 by the present writer on the bursa of this species. In a cross section 
 of P. sexalatus (fig. 25) Von Drasche shows that the projecting cuticle 
 forming the lateral wings has corresponding depressions inward. 
 
 Stossich's (1897b) description of P. sexalatus follows that of Molin 
 and Von Drasche. Piana (1897e), in an article on Simondsia para- 
 doxa, mentions finding two other species of nematodes in the same 
 bottle containing the specimens of Simondsia. He identified these 
 as being Spiroptera strongylina and PhysocepJialus sexalatus. These 
 .specimens were from an Italian pig.
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 25 
 
 Railliet and Henry's (191 Ib) description of Physocephalus sexa- 
 latus is based on specimens collected from a hog slaughtered at Hue", 
 Indo-China. These authors also report having observed it in material 
 from Madagascar in 1905. 
 
 Ciurea (1912) reported Spiroptera sexalata in domestic swine 
 slaughtered at Piatra Neamtz, Roumania, in 1910. Five out of 72 
 healthy swine were infested with from one to thirty of these para- 
 
 FIG. 21. Physocephalus sexalatus. Posterior 
 end of body of female, ventral view. a. , anus; 
 a. ut., anterior uterus; int., intestine; /. a. ut., 
 loop of anterior uterus; ov., ovary; p. ut., pos- 
 terior uterus. X 50. (Original.) 
 
 Jfomm. 
 
 FIG. 22. Physocephalus sexalatus. Ventral view of body of fe- 
 male in the region of the vulva, int., intestine; ut., uterus; 
 v., vulva; va., vagina. X 95. (Original.) 
 
 sites in the stomach. In three cases they were found associated 
 with Arduenna strongylina, and once with Gnafhostoma hispidum. 
 In this latter case the parasites were found in the ulcer caused by 
 G. Tiispidum. The worms were partially or entirely buried in the 
 mucosa, but no lesions were attributed to them. Ciurea's (1912) 
 .description and drawings of Physocephalus sexalatus agree in most 
 respects with the present writer's observations, the few differences 
 being noted in the course of this article.
 
 26 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 Seurat (1912) reports finding several hundred specimens of Spi- 
 roptera sexalata partially buried in the mucosa of the stomach of an 
 
 ass slaughtered in Algeria during July, 1911. 
 A subsequent examination of the fourth 
 stomachs of six dromedaries revealed numer- 
 ous specimens of this species hidden between 
 the folds of the mucosa, associated with 
 Hsemonchus contortus. While the description 
 of the specimens agrees in general with the 
 present writer's observations, the measure- 
 ments are all somewhat larger. The width 
 of the middle lateral wing (110 to 120 / as 
 given by Seurat) is over twice as great as 
 that given by the present writer, while the 
 vulva is described as located at the anterior 
 third of the body, instead of slightly posterior 
 of the middle, as described by Railliet and 
 Henry (191 Ib), Ciurea (1912), and Foster 
 (1912) (the present article). 
 
 Seurat (1912) also found in the dromedary 
 another form which he considers as a variety 
 and designates as var. cristata. This form 
 is distinguished from the typical species by 
 having four longitudinal crests on the head, 
 formed by four cuticular folds, and having four cuticular spines in 
 the mouth cavity. In this variety the position of the vulva is not 
 constant, but varies from the posterior 
 third of the body to an anterior position. 
 As Seurat's (1912) measurements of 
 Physocephalus sexalatus differ considerably 
 from the present writer's, and as the species 
 has hitherto been reported only in the 
 Suidse, it would seem desirable to reserve 
 an opinion until his statements can be 
 confirmed. 
 
 The stomach is the normal location for 
 Physocephalus sexalatus. Von Linstow 
 (1879b) reports Filaria strongylina as col- 
 lected from the small intestine of a hog 
 by Dr. V. Bering, of Stuttgart. As has 
 been shown, Von Linstow apparently con- 
 fused Physocephalus sexalatus with Ardu- 
 enna strongylina; it would seem there- 
 fore, that P. sexalatus may occasionally occur in the small intestine. 
 In most specimens examined by the author the cuticle of the head 
 appears as shown in fig. 18, which is closely similar to the form 
 
 FIG. 23. Physocephalus sexalatus. 
 Lateral view of egg removed 
 from a ruptured uterus, a. c., 
 albuminous covering; emb., 
 embryo; sh., shell. X 1,450. 
 (Original.) 
 
 FIG. 24. Physocephalus sexalatvt. 
 Bursa of male, ventral view. ad. p. , 
 adanal papillae; I. b. w., left bursal 
 wing; Z.sp.,longspicule; po. p., post- 
 anal papillae; pr. p., preanal papillae; 
 r. b. w., right bursal wing; s.sp., short 
 spicule. X280. (After Von Drasche, 
 1884a, Pl.XTV,flg.3.)
 
 THE ROUNDWORMS OF DOMESTIC SWIXE. 
 
 27 
 
 FIG. 25. Physocephalussexalattu. Cross 
 section through anterior part of body. 
 bd. w., body wall; I. c. w., lateral cu- 
 ticular wings. X 280. (After Von 
 Drasche, 1884a, PL XIV, fig. 4.) 
 
 depicted by Von Drasche (1884a). In about 20 per cent of the 
 specimens examined, however, the cuticle, from the lips to the 
 beginning of the lateral cuticular wings, 
 is inflated into two hemispherical vesicu- 
 lar wings (fig. 26). This second form is 
 not mentioned by Molin (1860b) or Von 
 Drasche (1884a), but possibly may be 
 referred to byDiesing (186 la) in the ex- 
 pression "epidermide in bullam inflata 
 tunicatum" in his description of the 
 genus PJiysocephalus. 
 
 The pharynx of P. sexalatus is about 
 three tunes as long and twice as broad as 
 that of Arduenna strongylina, and this, 
 together with the lateral wings character- 
 istic of the genus, are the salient points in 
 distinguishing the females of the two genera. At first sight the 
 ridges of the pharynx appear to form separate rings and are so 
 
 described by Von Linstow 
 (1879b and in liti) . By careful 
 focusing, however, it is seen 
 that these ridges form a simple 
 spiral at the anterior end of the 
 pharynx and after making four 
 or five turns split up into sepa- 
 rate rings. At the posterior 
 end of the pharynx they are 
 again joined into a simple spiral 
 (fig. 18) . The final loop of the 
 anterior spiral forms the first 
 ring of the series, and the begin- 
 ning of the posterior spiral takes 
 its origin from the lower part of 
 the last ring. The number of 
 loops to the spirals and the num- 
 ber of sep arate rings is sub j ect to 
 considerable variation. A rather 
 extreme case is seen in fig. 27. 
 Here the first spiral has five 
 loops followed by a detached 
 ring. This in turn is followed 
 by a spiral of four loops, after 
 which are two detached rings. 
 The final spiral consists of 11 
 continuous loops. In every case, however, so far as observed, the ridges 
 form both spirals and rings, commencing and ending with a spiral, and 
 
 FIG. 26. Physocephalus sexalatus. Ventral view of body 
 offemale. a., anus; c.cut. inf., cervical cutieular infla- 
 tion; 1. c. w., lateral cuticular wings; p., vulva. X 7. 
 (Original.)
 
 28 
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 not a series of parallel bands, as described by Von Linstow (1879b) , or a 
 
 continuous spiral, as described by Von Drasche (1884a), Railliet and 
 
 Henry (191 Ib), and Ciurea (1912). 
 
 Railliet and Henry (191 Ib) mention two asymmetrical cervical 
 
 papillaB, the right papilla being 220 /* and the left 420 JM from the 
 
 anterior end. As seen by the present 
 writer the left papilla has a broad 
 base and a blunt point and pene- 
 trates the cuticle 281 /i from the an- 
 terior end, or a little anterior of the 
 base of the cephalic inflation. The 
 right papilla was not seen by the 
 present writer, but on the right side, 
 not far from the location of the papilla 
 as given by Railliet and Henry 
 (191 Ib), the excretory canal opens. 
 The end of the canal is a slender 
 tube penetrating the middle lateral 
 wing and looking not unlike a long 
 stalked papilla (fig. 18). Its true 
 nature has been shown by Ciurea 
 (1912), who made a cross section of 
 the. worm at this point. The lateral 
 situation of the excretory pore is ap- 
 parently unique among nematodes, 
 the usual situation being ventral. 
 
 The lateral cuticular wings unite 
 just posterior of the base of the ce- 
 phalic inflation (fig. 18). Here the 
 cuticle forms an inverted pocket like 
 the handle of a table drawer (fig. 27). 
 The lateral cuticular wings are densely 
 striated at the base, giving them a 
 puckered appearance. Although the 
 cuticle of the entire body is striated, 
 these striations appear more promi- 
 
 ey 
 
 wings; n. r., nerve ring; ph., pharynx. 
 X 150. (Original.) 
 
 lomm 
 
 FIG. 27. Physocephalus sexalatus. Lateral 
 view of anterior end of body. c. cut. inf., 
 cervical cuticular inflation; cut., cuticle; 
 es., esophagus; ex. p., excretory pore; lab. -, , . 
 
 P., labial papiii; i. c. ., lateral cuticular nently on the lateral wings, particu- 
 larly at their base, than elsewhere. 
 The esophagus, about four-fifths of 
 the length of the lateral wings, is densely striated transversely, 
 with a very narrow lumen; nerve ring 439 // from the anterior end 
 (fig. 18). The intestine is more or less convoluted throughout its 
 course, especially posteriorly. 
 
 The male (fig. 28) is about half the length of the female, but as 2 
 to 3 mm. of the posterior end is twisted into a spiral, its apparent 
 length is much shortened.
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 29 
 
 The spiral of the caudal end of the male appeared in a few cases as 
 a single coil like that of Arduenna strongylina. In other cases it con- 
 sisted of an irregular double twist (fig. 28). In the greater number 
 of specimens examined, however, it formed a broad open spiral like 
 a corkscrew (fig. 19). Comparing the spiral to the thread of a screw, 
 and considering the tip of the tail as the point of the screw, the spiral 
 resembles a left-handed screw with three (rarely four) threads; no 
 cases were seen in which the spiral 
 revolved in the opposite direction. 
 
 The bursal wings are described 
 as symmetrical by Railliet and 
 Henry (191 Ib) and are so depicted 
 by Von Drasche (1884a). The right 
 wing is, however, a little longer than 
 the left wing (fig. 19). Ciurea (1912) 
 considers that it is also narrower, 
 but this statement could not be veri- 
 fied by the present writer. Ciurea 
 (1912) states that the bursal wings 
 extend throughout the twisted por- 
 tion of the tail. As seen by the 
 present writer they extend only about 
 half this distance (fig. 19). The 
 cuticle on the ventral side of the 
 male (fig. 19), commencing at some 
 distance anterior of the spiral, is 
 marked with longitudinal striations 
 intercepted by transverse lines, ap- 
 pearing under high power as longi- 
 tudinal folds of the cuticle separated 
 by transverse ridges. A similar struc- 
 ture has already been noted on the 
 ventral surface of Arduenna strongy- 
 lina (fig. 2) . As in most nematodes, 
 the papillae are arranged symmetri- 
 cally on either side of the median 
 line. Their grouping and structure 
 have already been discussed. 
 
 The intestine is much convoluted, growing broader close to the 
 cloaca. The vesicula seminalis occupies most of the body cavity in 
 the posterior end, maintaining a fairly uniform diameter until it 
 disappears dorsal of the intestine which conceals the ductus ejacu- 
 latorius. The long convoluted testis which extends to the middle of 
 the body presents no specific characteristic features. The anus is 
 
 I- 
 
 mm. 
 
 FIG. 28. Physocephalus sexalatus. General 
 view of body of male. 5. , bursa; es. , esoph- 
 agus; *p*.,spicules. X 23. (Original.)
 
 30 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 circular, like that of Arduenna strongylina, but not surrounded by a 
 serrated ring. 
 
 I The vulva (35 ft in diameter), as in Arduenna strongylina, appar- 
 ently occupies a somewhat lateral rather than ventral position, open- 
 ing toward the right side (fig. 22). It is situated just below the 
 middle of the body, dividing the worm in the ratio of 9 to 8. Accord- 
 ing to Ciurea (1912) the cuticle in the region of the vulva is marked 
 with longitudinal thickenings which may interlock with the cuticular 
 ridges on the ventral surface of the male, and thus assist in maintain- 
 ing the position of the male in copulation. The vagina, extending 
 posteriorly along the right side, is at first 50 ft in diameter, but gradu- 
 ally broadens to 105 ft at its posterior end, where it disappears from 
 the ventral side, extending dorsal of a lobe of the uterus. The dis- 
 tance from the vulva to this point is 976 /*. The wall of the vagina 
 is relatively thick, composed of transverse muscle fibers. The lumen 
 is 20 // in diameter. Eggs containing well-developed embryos 
 ready to pass out could be seen in single file in the lumen of the 
 vagina near the opening (fig. 22). Railliet and Henry (191 Ib) 
 describe the vulva as opening posteriorly at the limit of the third 
 and four fifths of the body. Von Linstow (in litt) places it somewhat 
 posterior of the middle of the body, dividing the worm in the ratio 
 of 10 to 9. 
 
 The arrangement of the uteri and ovaries in the body of the female 
 is, so far as could be seen, similar to that of Arduenna strongylina. 
 The convoluted ovary of the posterior uterus occupies the caudal 
 extremity of the worm, its terminus disappearing dorsal of the pos- 
 terior uterus. A loop of the anterior uterus extends nearly to the 
 caudal end. The exact length of the vagina was not determined. 
 A loop of the posterior uterus, corresponding to the loop of the anterior 
 uterus, lies underneath the anterior uterus and extends nearly to its 
 terminus. The union of the vagina with the uteri was not seen, nor 
 was the anterior ovary traced throughout its length. While neither 
 uterus was followed throughout its entire length, the two termini, 
 one posterior the other anterior, the posterior uterine loop, and the 
 anterior loop, are all similar to the arrangement seen more clearly in 
 Arduenna strongylina. 
 
 Ciurea (1912) depicts a pluglike protuberance at one of the poles 
 of the eggs of Physocephalus sexalatus, which bears a superficial re- 
 semblance to the operculum of a Trichuris egg, but does not penetrate 
 the eggshell as in the latter case. This feature was not seen by the 
 present writer; however, a faint transverse line could be seen at 
 either pole (fig. 23), which apparently is the line of fissure along which 
 the shell breaks when the embryo is liberated.
 
 THE EOUNDWORMS OF DOMESTIC SWINE. 31 
 
 COMPARISON OF PHYSOCEPHALUS SEXALATUS AND ARDUENNA 
 
 STRONGYLINA. 
 
 The following comparison of appearances of Arduenna strongylina 
 and Physocephalus sexalatus will assist in separating the two species 
 without the aid of a magnifier. 
 
 Males. Tail of Physocephalus sexalatus ending in a spiral, Ardu- 
 enna strongylina ending in a single coil; PJiysocephalus sexalatus 
 shorter and slenderer than Arduenna strongylina. 
 
 Females. PJiysocephalus sexalatus straight, or nearly so; speci- 
 mens preserved in alcohol when lifted out of a petri dish with a 
 needle bend sharply in the middle. Body slenderer than Arduenna 
 strongylina, except toward the posterior end, which is thicker and 
 blunter. 
 
 Alcohol specimens of Arduenna strongylina are usually curved in a 
 half circle. They are thicker in the middle of the body than Physo- 
 cephalus sexalatus and pointed at both ends. On being lifted with a 
 needle they do not collapse like PJiysocephalus sexalatus, but maintain 
 their crescentic shape. 
 
 As has already been stated, Molin (1860b) was the first to distin- 
 guish this species from Arduenna strongylina, with which it had been 
 confused by Diesing (185 la). Besides the specimens from the white- 
 lipped peccary, Molin (1860b) also found two females of this species 
 in a bottle containing specimens of Arduenna strongylina collected 
 by Bremser from the stomach of the wild boar and deposited in the 
 Vienna Museum. That it has only twice been reported in Europe 
 in association with Arduenna strongylina is perhaps due to confusion 
 of the two species, an error which appears to have occurred in at least 
 one case (Von Linstow, 1879b). In the United States it has been 
 found in nearly every case in which specimens of Arduenna strongylina 
 have been collected. 
 
 OTHER SPECIES REFERRED TO PHYSOCEPHALUS SEXALATUS. 
 
 Two other worms have been thought by different writers to be possi- 
 bly identical with Physocephalus sexalatus, viz, Simondsia paradoxa 
 (Cobbold, 1864b) from Sus scrofa domestica and Filaria nitidulans 
 (Schneider, 1866a) from Tapirus americanus. 
 
 Simondsia paradoxa was collected from the stomach of a German 
 hog kept at Regent's Park, London, and was described by Cobbold 
 (1864b). In a later work (1879b) Cobbold suggests the possibility 
 of the worm being identical with Physocephalus sexalatus. The 
 immensely hypertrophied uterus of Simondsia paradoxa, forming a 
 rosette entirely covering the caudal end of the female, however, clearly 
 differentiates this species from Physocephalus sexalatus.
 
 32 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 In his description of Physocephalus, Von Drasche (1884a) suggests 
 the possibility that Schneider's (1866a) Filaria nitidulans may be 
 identical with P. sexalatus. Both worms are characterized by three 
 lateral wings on either side, and the caudal extremity of the males of 
 both species are alike in the number and arrangement of the papillae. 
 The measurements of Filaria nitidulans (males 20 mm., females 32 
 mm.) are, however, far in excess of the measurements for Physo- 
 cephalus sexalatus, and the position of the vulva of Filaria nitidulans 
 is stated as "directly above the anus," while the vulva of Physo- 
 cephalus sexalatus is slightly posterior of the middle of the body. 
 Ciurea (1912), who has recently reexamined Schneider's material, was 
 unable to determine the location of the vulva of F. nitidulans. He 
 gives, however, a summary of the differences between Filaria nitidu- 
 lans and Physocephalus sexalatus, proving conclusively that they be- 
 long to different species, although he considers that Filaria nitidulans 
 should be included in the genus Physocephalus. Stossich (1897b), fol- 
 lowing Von Drasche's (1884a) suggestion, considered the worms 
 identical. He listed Tapirus americanus as a host of Physocephalus 
 sexalatus and combined Molin's (1860b) measurements of P. sexalatus 
 with Schneider's (1866a) measurements of Filaria. nitidulans. 
 
 DISTRIBUTION OF ARDUENNA STRONGYLINA AND PHYSOCEPHA- 
 LUS SEXALATUS IN THE UNITED STATES. 
 
 Of nine lots of Arduenna strongylina collected in various parts of 
 the United States and now deposited in the helminthological collection 
 of the Bureau of Animal Industry, only two have been found not to 
 contain examples of Physocephalus sexalatus, and both of these lots 
 contain only a few specimens. The distribution of Arduenna strongy- 
 lina is therefore similar to that of Physocephalus sexalatus, since the 
 latter species, according to the writer's experience, is practically always 
 associated with the former. 
 
 To determine the distribution of these parasites and the frequency 
 of their occurrence in the United States the literature was searched 
 for references to Spiroptera strongylina. Four such references were 
 found, as below; in most cases Physocephalus sexalatus was probably 
 also present but not recognized. 
 
 1. Curtice (1892g), in a list of parasites infesting domestic animals 
 and man in the United States, includes the following entry : "Spiroptera 
 strongylina. Hud. Host, Sus scrofa domestica. Location, stomach," 
 followed by the remark, "Is often found with the food and attached to 
 the walls." Specimens No. 2058 of the helminthological collection of 
 the Bureau of Animal Industry were collected and identified by Cur- 
 tice as Spiroptera strongylina. These specimens have been examined 
 by the writer, who verified Dr. Curtice's identification. A few exam- 
 ples of Physocephalus sexalatus were also present.
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 33 
 
 2. Stiles and Hassall (1894e) include Spiroptera strongylina in their 
 preliminary catalogue of the parasites in the collection of the United 
 States Bureau of Animal Industry. They report the parasite as com- 
 mon. The specimens referred to by them (No. 2057 of the bureau 
 collection) have been reexamined by the writer, and many specimens 
 of Physocephalus sexalatus were found with the specimens of Arduenna 
 strongylina. Stiles and Hassall's specimens were collected at Ben- 
 ning, D. C. 
 
 3. Francis (1894a) reported Spiroptera strongylina in a list of para- 
 sites collected by him in Brazos County, Tex. It is reported as com- 
 mon. The specific name is followed by an interrogation point in 
 parenthesis to indicate the author's doubt as to the correctness of the 
 identification. Considering the inaccuracy of the descriptions of 
 Arduenna strongylina, then available, it is not to be wondered that 
 Francis, noticing the discrepancies between the descriptions and the 
 anatomical features seen in his specimens, should question the identi- 
 fication. On the other hand, it is quite possible that the specimens 
 collected by Francis were Physocephalus sexalatus, or included this 
 species. 
 
 4. Kaupp (1910) reported the occurrence of Spiroptera strongylina 
 in hogs raised in the Missouri Valley. His article is illustrated with 
 original drawings, one of which shows the caudal end of the female 
 with the vulva apparently on the right side, a little anterior of the 
 anus. 
 
 For the sake of additional data, letters were sent to the inspectors 
 in charge at some of the principal slaughterhouses of the United 
 States, requesting information in regard to the occurrence of Spirop- 
 tera strongylina in hogs. Replies were received from South Omaha, 
 Chicago, St. Louis, and Kansas City. The inspector in charge at 
 South Omaha reported that fully 80 per cent of the hogs examined 
 were infested. It was reported from St. Louis that "the worms 
 occur in considerable numbers in the mucous coating of the stomach." 
 The parasite is reported as very frequent in hogs slaughtered at 
 Kansas City; out of 1,450 hogs examined, 1,052 were infested. In 
 some stomachs as many as 140 worms were collected. From Chicago 
 it was reported that 1,000 hogs had recently been examined, and 690 
 were found infested. The worms were found on the surface of the 
 mucous membrane or attached by the head. Several hundred 
 specimens obtained by scraping the mucosa from the stomachs of a 
 number of infested hogs were received from this city. These worms 
 were found to be Arduenna strongylina and Physocephalus sexalatus. 
 
 Reports from slaughterhouses regarding the occurrence* of parasites 
 are of but little value in determining the localities infested by a given 
 parasite, as the animals slaughtered are received from widely scat- 
 tered sections of the country. Enough data have been gathered,
 
 34 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 however, to warrant the assertion that the parasites occur throughout 
 the middle and southwestern (and probably eastern) United States. 
 Specimens have been collected by Hall in 1908 from a hog kept at 
 Bethesda, Md., in all probability of eastern origin. They have also 
 been collected by Kilborne at Washington, D. C., and by Stiles and 
 Hassall at Benning, D. C. ; in the latter case, however, it is possible 
 that the host animal had been shipped to the local slaughterhouse 
 from a Western or Central State. 
 
 RELATIVE FREQUENCY OF THE TWO SPECIES. 
 
 That Physocephalus sexalatus occurs less abundantly than Arduenna 
 strongylina in American swine is indicated by the following data : 
 
 All the worms contained in a bottle of specimens forwarded from 
 Chicago were sorted out by species and sex. The bottle contained 
 744 specimens. Of these, 599, or approximately 80 per cent, were 
 Arduenna strongylina, and the remaining 145, or 20 per cent, were 
 Physocephalus sexalatus. Of the 599 specimens of Arduenna strongy- 
 lina, 399, or 56 per cent, were females, and 260, or 44 per cent, were 
 males. A smaller percentage of males was found among the speci- 
 mens of Physocephalus sexalatus. Of the 145 specimens found, 69 
 per cent were females and 31 per cent were males. 
 
 LESIONS ASSOCIATED WITH ARDUENNA STRONGYLINA, ARDUEN- 
 NA DENTATA, AND PHYSOCEPHALUS SEXALATUS. 
 
 From an economic standpoint these three species are^probably of 
 considerable importance. Prior to 1899 it was not considered that 
 Arduenna strongylina was especially injurious to swine. Neumann 
 (1892a), in mentioning that Spiroptera strongylina caused small sub- 
 mucous tumors of the stomach and that no morbid disturbances were 
 attributed to it, summed up the general opinion of the time regarding 
 the economic importance of the parasite. More recent reports, 
 however, indicate that these parasites should be regarded as the 
 possible etiology of serious gastric disorders. 
 
 Von Ratz (1899d) found Spiroptera strongylina very common 
 among swine hi Hungary, and attributed to this parasite several 
 epizootics of a rather serious nature, in one of which, out of a herd of 
 230 sows, 21 were seriously affected and 6 died. Some of the symp- 
 toms were described as follows: 
 
 The diseased sows suffered from loss of appetite, eating very little and in the worst 
 cases finally refusing all food; on the other hand, they drank water excessively and 
 were very restless, continually pawing the ground. 
 
 Describing the post-mortem lesions seen in the stomach, Von Ratz 
 says: 
 
 At the pyloric end the mucous membrane was covered with a thick, lamellous, 
 firmly adhering pseudomembrane, which upon being removed revealed a superficial 
 loss of tissue of the mucous membrane. Under the mucous membrane lay numerous
 
 THE BOUNDWORMS OF DOMESTIC SWINE. 35 
 
 Spiroptera strongylina fastened partly in the stomach wall, partly in the pseudo- 
 membrane. In addition to these lesions, dark red spots the size of a penny were to be 
 seen, corresponding to which were numerous openings the size of a needle prick, 
 through which projected the bodies of the nematodes. 
 
 While no data are at hand regarding the effect of Arduenna dentata 
 on its host, hi view of its close similarity with Arduenna strongylina 
 and the fact that both species are parasitic in the stomach, it may be 
 assumed that the former species is as injurious as the latter. 
 
 Railliet and Henry (19 lib) report that the stomach of a sow from 
 Madagascar from which specimens of PJiysocephalus were collected, 
 presented a very intense gastritis with a quantity of small elevations 
 on the mucosa. 
 
 The information and material supplied by the inspectors of this 
 bureau have shown that lesions of a nature similar to those described 
 by Von Ratz are frequently associated with the presence of Arduenna 
 strongylina in this country. 
 
 The inspector in charge at South Omaha reported that "Ten per 
 cent of the affected stomachs show a highly inflamed zone surround- 
 ing the infested area, and hi a few instances considerable ulceration 
 exists." The inspector in charge at St. Louis was of the opinion 
 that "they produce no apparent lesions." The inspector in charge 
 at Chicago forwarded, in addition to the loose specimens already 
 mentioned, several pieces of hogs' stomachs showing the worms in 
 situ. The heaviest infestations were found hi portions from the 
 pyloric end of the stomach, which in one instance presented the 
 folio whig appearances: A piece of stomach from the pyloric end 
 about 21 cm. wide by 20 cm. long contained a cluster of worms buried 
 in a glairy mucous mass of yellowish color firmly attached to the normal 
 mucous membrane, and forming, hi the opinion of pathologists in the 
 Pathological Division of this bureau, to whom the tissues were referred, 
 a pseudomembrane of necrotic tissue. Several such worm clusters 
 were observed on the portion examined, the worms in nearly every 
 case being buried in a mass of mucus, and appearing as bright red 
 lines in the yellowish mass. (See PI. I.) In places the necrotic 
 tissue had apparently sloughed off, leaving deep, red, depressed areas 
 of irregular shape. These areas varied in size from a few millimeters 
 to 2 or 3 centimeters in diameter. The same lesions could be observed 
 under the necrotic tissue when this had been removed with forceps. 
 The condition was described by one of the pathologists as "undoubt 
 edly ulcerous." 
 
 It was suggested by the pathologists who examined the material 
 that the pseudomembranes might have been caused by Bacillus 
 necrophorus gaining an entrance to the submucosa as the result of the 
 piercing of the mucous membrane by the parasitic worms; examina- 
 tions of scrapings from the stomach lesions revealed a few specimens 
 of the bacillus. As explained by Mohler and Morse (1904), this
 
 36 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 bacillus is normally found in the stomachs of hogs and other animals, 
 and while under ordinary circumstances it has no pathological effect, 
 if enabled through some lesion to the mucous membrane to gain 
 access to impaired tissue, its proliferation results in the sloughing of 
 the mucous membrane and the formation of ulcers. 
 
 Mohler and Morse (1904), describing necrobacillosis of the digest- 
 ive tract, state: "The necropsy in such cases revealed hemorrhages 
 and erosions in the stomach, but no areas of coagulation, ' ' an accurate 
 description of the conditions found by the present writer. The char- 
 acteristic odor described for lesions of Bacillus necrophorus was only 
 faintly present, being modified perhaps by the boric acid with which 
 the specimen was sprinkled and which may account for the paucity 
 of the parasitic flora found. 
 
 How deeply Arduenna strongylina is capable of penetrating into the 
 submucosa was well shown in one of the specimens forwarded from 
 Chicago. A piece of the cardiac portion of the stomach contained 
 a worm 12 mm. long which had bored diagonally into the mucosa to a 
 depth of 10 mm., only the caudal end projecting above the "surf ace. 
 The hole made was similar to a pin prick, a simile used by Von Ratz 
 (1899d) in describing the lesions observed by him. Indeed Von 
 Ratz's description is practically identical with the conditions found 
 by the present writer. 
 
 The habit of boring into the mucosa characteristic of these para- 
 sites would seem an ideal method of inoculating the submucosa of the 
 host with Bacillus necrophorus if any were present, and this, consid- 
 ered in connection with the conditions observed in infested stomachs, 
 indicates that the worms may be the indirect cause of grave ulcera- 
 tion. Considered apart from their possible r61e as infective agents, 
 the mechanical injury to the stomach walls due to the penetration of 
 the worms in numbers would seem to be a serious factor even if the 
 worms were unassociated with bacilli. Moreover, the livid red color 
 of the worms in situ in the stomachs examined would seem to indicate 
 that they feed on blood, an additional reason for regarding them as 
 dangerous parasites. The whole question, however, of the patho- 
 genicity of the parasites, and as to their relationship to the lesions 
 observed, remains open for further investigation. 
 
 An examination of the stomach portions received showed specimens 
 of Physocephalus sexalatus attached in the same manner as already 
 noted for Arduenna strongylina; hence the former parasite may be 
 considered only less dangerous than the latter, as it is less abundant. 
 
 LIFE HISTORY. 
 
 Nothing is known in regard to the development of the worms from 
 the egg to the adult. The wide distribution, the frequency of the 
 parasites, and the similarity of the eggshell to that of an ascarid,
 
 THE ROUNDWOEMS OF DOMESTIC SWINE. 37 
 
 suggest the possibility that development occurs without an inter- 
 mediate host. From the fact that the embryos are well developed in 
 the uterus before oviposition, it would seem that but little time is 
 required for incubation, and the thickness of the shell would indicate 
 the necessity of the gastric juice of the host to dissolve the shell and 
 liberate the embryo. 
 
 PREVENTIVE MEASURES. 
 
 In the absence of knowledge as to the life cycle of the parasites, no 
 prophylaxis or treatment specially adapted to the case can be formu- 
 lated. The following general prophylactic measures are suggested: 
 
 1. Hogs suffering from loss of appetite or failing to fatten under 
 proper food and hygiene should be examined for evidence of infection 
 by killing one or two and looking in the stomach for worms; or, where 
 practicable, the feces of the entire herd may be examined micro- 
 scopically. 
 
 2. Those swine found infested with stomach worms should be 
 isolated from noninfested or presumably noninfested swine in clean 
 pens, and the dung removed daily and mixed with quicklime or 
 disposed of by carting it to places to which hogs do not have access. 
 
 3. The noninfested swine should not be allowed to remain in the 
 same pens formerly occupied by the infested animals, but should have 
 clean quarters. The old pens should be thoroughly disinfected with 
 lime after removing the dung and burning over the ground where 
 feasible. 
 
 MEDICINAL TREATMENT. 
 
 Youatt (1847c), referring to Spiroptera strongylina, recommends 
 turpentine and salt with the food for treating these worms. Coal-tar 
 creosote, gasoline, and copper sulphate have been found more or less 
 efficacious in treating stomach worms (Hsemonchus contortus) in sheep, 
 and similar treatment might be tried on pigs (see Bureau of Animal 
 Industry Circular 102). Santonin and calomel, 3 grains each per 
 hundred pounds of body weight, given after a fast of 12 to 16 hours, 
 is another remedy which deserves trial. 
 
 Whatever drug is used should first be given in small quantities and 
 tried on a few of the most heavily infested swine, the size of the dose 
 being increased as occasion demands.
 
 38 THE ROUND WORMS OF DOMESTIC SWINE. 
 
 KEY TO THE ROUNDWORMS PARASITIC IN DOMESTIC SWINE. 
 
 The arrangement of the following key to the roundworms which 
 have been reported by various authors as parasites of hogs is purely 
 artificial and arbitrary and indicates nothing as to the systematic 
 relationship of the different forms. A classified list of the round- 
 worms of swine is given later on page 41. 
 
 Section. 
 
 Parasitic in alimentary tract 1 
 
 Parasitic in respiratory tract 16 
 
 Parasitic in other organs 17 
 
 1. Diameter of body at middle over 3 mm 2 
 
 Diameter of body at middle less than 3 mm 3 
 
 2. Anterior extremity furnished with a protractile prolwscis covered with spines. 
 
 Male 6 to 10 cm. long, 3 to 5 mm. in diameter. Female 20 to 35 cm. long, 
 4 to 9 mm. in diameter. Eggs, 87 to 100 n long, subcylindrical, smooth, 
 with 3 envelopes. In small intestine, usually attached to the mucous 
 
 membrane Gigantorhynchus hirudinareus. 
 
 Anterior extremity without protractile proboscis. Mouth with 3 prominent 
 lips. Male 15 to 17 cm. long, 3 to 3.2 mm. thick. Female 20 to 25 cm. 
 long, 5 to 5.5 mm. thick. Eggs oval, 66 fi long, thick-shelled, surface cov- 
 ered with mammillate projections. In small intestine, sometimes in biliary 
 tract and pancreas Ascaris suum. 
 
 3. Less than 5 mm. in length 4 
 
 Over 5 mm. in length 5 
 
 4. Vulva anterior of middle of body. Ovoviviparous. Females 3 to 4 mm. 
 
 long, 60 fi in diameter. Males 1.4 to 1.6 mm. long, 40 /z in diameter, with 
 a short finger-like process on each side of the anal opening. Adults in 
 
 small intestine, larvae encysted in skeletal muscles Trichinella spiralis. 
 
 Vulva posterior of middle of body. Females (parthenogenetic; parasitic 
 males lacking) 3.75 mm. long, 80 fi in diameter. Eggs 45 fi long by 25 /t 
 broad, with thin shells. In small intestine Slrongyloides suis. 1 
 
 5. Head covered with spines; separated from the body by a deep constriction. 
 
 Male 15 to 25 mm. long. Female 22 to 31 mm. long. Eggs 70 fi long by 39 
 
 fi wide. In stomach Gnathostoma hispidum. 
 
 Head without spiny armature 6 
 
 6. Posterior end of body of female with relatively large rosette-like excrescence 
 
 containing the hypertrophied uterus. Male 12 mm. long. Female 15 mm. 
 
 long. In stomach Simondsia paradoxa. 2 
 
 Posterior end of body of female without uterine rosette 7 
 
 7. Anterior portion of body slender, like a whiplash, about twice as long as the 
 
 thicker posterior portion. Male with single spicule. Male 33 to 40 mm. 
 long. Female 34 to 50 mm. long. Eggs 52 to 56 /* long, ellipsoidal, with 
 an opening at each pole closed by a plug-like operculum, and brownish in 
 
 color. In cecum Trichuris suis. 
 
 Body continuous, not flagelliform anteriorly. Male with two spicules 8 
 
 1 While Strongyloides papillosvs (= Trichosoma papiUosum Wedl.)a parasite of sheep has frequently been 
 reported for the pig, this is probably the result of confusion with Strongyloidu suis. The Stronyyloides of 
 the pig Is somewhat larger than the form found in sheep. 
 
 * Included by the present writer among the Filariidse on account of the inequality of the spicules. Its 
 position in this family is not, however, defin tely established. See footnote on page 9, second paragraph.
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 39 
 
 Section. 
 
 8. Male with two equal or subequal spicules; tail with membranous bursa sup- 
 
 ported by paired rays and eggs with thin shells 9 
 
 Male with two spicules of very unequal length; tail with lateral longitudinal 
 bursal membranes supported by stalked pappillse. Eggs with thin or thick 
 shells 12 
 
 9. Mouth enlarged to forma buccal capsule 10 
 
 Mouth small; buccal capsule not present. Male 5 mm. long. Female 8 to 8.5 
 
 mm. long. Spicules 130 /j. long. Vulva about 2 mm. from the tip of the 
 tail. Eggs, 45 fi long by 36 (JL wide. In stomach "Strongylus" rubidus. 1 
 
 10. Buccal capsule broader than long, mouth bordered by a crown of numerous, 
 
 small, pointed processes. Male 8 to 12 mm. long. Female 12 to 15 mm. 
 long. Spicules slender, 1.13 mm. long. Vulva a short distance in front of 
 anus, piptuberant. Adults in large intestine, larvae encysted in the wall 
 of the large and small intestines, forming nodules. .(Eesophagostomum dentatum. 
 Buccal capsule spherical or elongated , border of mouth smooth 12 
 
 11. Buccal capsule spherical. Male 7 mm. long, 0.2 mm. thick. Female 8 mm. 
 
 long, 0.3 mm. thick. Vulva prominent. In small intestine. 
 
 Globocephalus longemucronatus. 
 
 Buccal capsule elongated, oval. Male 4.4 mm. long, 0.38mm. thick. Female 
 6.5 mm. long, 0.52 mm. thick. Spicules 590 /t long. Vulva sunken. In 
 small intestine Crassisoma urosubulatum. 
 
 12. Anterior end of body supplied with numerous cuticular tubercles or shields. . 13 
 Anterior end of body without cuticular tubercles 14 
 
 13. Male 30 to 50 mm. long by about 250 /JL thick. Female 80 to 145 mm. long, 
 
 300 to 350 fjL thick. Left spicule 16 to 17 mm. long; right spicule 140 to 180 fj. 
 long. Vulva 4 to 5 mm. from tip of the tail. Eggs 55 to 60 ft long by 32 to 
 36 [i wide. In the mucosa of the esophagus and pharynx. 
 
 Gongylonema scutatum. 2 
 
 Male 14 to 50 mm. long, 175 to 195 fj. thick. Female 37 to 40 mm. long (? or 
 longer), 350 n thick. Left spicule 4 to 5 mm. long, right spicule 84 to 110 
 fj. long. Vulva about 2 mm. from the tip of the tail. Eggs 52 to 56 , long 
 by 32 fj. wide. In the mucosa of the esophagus and pharynx. 
 
 Gongylonema pulchrum. 
 
 14. Body furnished anteriorly with six longitudinal lateral wings, three on each 
 
 side, the middle wing of each three wider than the other two. Ridges of 
 pharynx forming a simple spiral, breaking up into separate wings. Male 
 6 to 9 mm. long. Female 13 to 19 mm. long. Spicules 2.1 to 2.25 mm . long, 
 and 300 to 350 /t long, respectively. Vulva anterior of the middle of the 
 body. Eggs 34 u. long by 15 , wide, with rather thick shells. In stomach. 
 
 Physocephalus sexalatus. 
 
 Anterior portion of body with a single longitudinal wing. Ridges of pharynx 
 forming a continuous multiple spiral 15 
 
 1 "Strongylus" rubidus does not belong in the genus Strongylus. Its proper position is in the family 
 Trichostrongylinse. As yet, however, no genus has been established to which it may be assigned. 
 
 * Reported by Korzil (1877a) and Piana (1896b). According to Neumann (1894d), however, the measure- 
 ments given by Korzil indicate that the species studied by him is Gongylonema pulchrum, Molin 1857. 
 The measurements given by Piana(1896b) are, males 60 to 80 mm. long by 130 ft broad; females 80 to 145mm. 
 long, 600 n broad. Except that G. pulchrum is smaller than G. scutatum, there is but little morphological 
 difference between the two species. The species are considered identical by Railliet (1893a), although this 
 view is not accepted by Neumann (1894d) and others. G. scutatum is normally a parasite of ruminants.
 
 40 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 Section. 
 
 15. Male 10 to 15 mm. long. Female 16 to 22 mm. long. Long spicule 2.24 U> 
 2.95 mm. in length, 5 to 6 times as long as the short spicule. Vulva some- 
 what anterior of the middle of the body. Eggs 34 to 39 p long by 20 ft wide, 
 
 with rather thick shells. In stomach Arduenna strongylina. 
 
 Male 25 to 35 mm. long, 700 to 800 /j. broad. Female 40 to 55 mm. long, 1.1 to 
 1.2 mm. broad. Long spicule 3.75 to 4.23 mm. long. Short spicule 540 to 
 650 ft long. Vulva three-eighths of the distance from the anterior end. 
 
 Arduenna dentala. 
 
 16. l Spicules about 4 mm. long, each terminated by a single hook. Vagina about 
 
 2 mm. long. Male between 12 and 25 mm. in length. Female between 20 
 and 50 mm. in length. Vulva near anus. Eggs between 57 and 100 /t in 
 length and 39 and 73 ft. in width. In trachea and bronchi.. Atetastrongylus apri. 
 Spicules 1.5 mm. long, each terminated by a double hook. Vagina about 
 500 [i Jong. Male between 12 and 25 mm. in length. Female between 
 20 and 50 mm. in length. Vulva near anus. Eggs between 57 and 100 fi 
 in length and 39 and 72 fi in width. In trachea and bronchi. 
 
 Mctastrongylus bremvaginatus. 
 
 17. 2 Encysted in skeletal muscles, microscopic in size. Cysts slightly elongated, 
 
 ovoid, long axis parallel to the muscle fibers, about 400 fi long by 250 fi broad. 
 
 Trichinella spiralis (larvae). 
 
 Free in peritoneal cavity, in kidneys, in ureters, in the bladder, or encysted 
 in fat of kidneys or loins 18 
 
 18. Male under 40 mm. long 19 
 
 Male over 12 cm. long 20 
 
 19. Male 25 to 37 mm. long. Female 37 to 40 mm. long. Two spicules, equal or 
 
 subequal, about 0.8 mm. long. Vulva less than 2 mm. from the tip of the 
 tail. Eggs 100 fi long by 56 fi wide, with thin 'shells. In kidneys, ureters, 
 and encysted in fat of kidneys and loins Stephanurus dentatus. 
 
 20. Male 14 to 40 cm. long, 4 to 6 mm. in diameter. Female 20 cm. to 1 m. long, 
 
 5 to 12 mm. in diameter. Spicule single, 5 to 6 mm. long. Vulva near the 
 anterior end of the body. Eggs 64 to 68 ft long by 40 to 44 ft wide, thick- 
 shelled, with pitted surface. In kidneys, ureters, peritoneal cavity, or 
 
 bladder Dioctophyme visceralis. 3 
 
 Male 10 to 11 cm. Greatest diameter, 650 fi. Tail twisted in a loose spiral 
 with a pointed end; 8 pairs of papillae, 4 preanal and 4 postanal. Spicules 
 unequal, the longer 215 ft long, 25 fi broad, with a membraneous extension 
 70 fi long. Short spicule 140 fi long, 52 ft broad. Female 20 to 21 cm. long. 
 Vulva 600 fi from the anterior extremity. Anus 300 fi from the posterior 
 extremity. Eggs ovoid, 45 by 26 ft when fully developed. Viviparous. 
 Parasitic in the peritoneal cavity Setaria bernardi. 
 
 1 Railliet and Henry, 1911, describe a new species, Filaria bauchei, found in the "lungs "of a hog slaughtered 
 at Hud, Indo-China. The location of the parasite is not definitely known. The female alone was found. 
 It is reported as 22J cm. long, with a maximum diameter of 635 ft. The body is transversely striated, the 
 striae being 5 to 6 / apart. Mouth unarmed, funnel-shaped, the cuticle thickened at the anterior end. Anus 
 155 p. from the posterior extremity; vulva 1. 1 mm. from the mouth. 
 
 8 GigantorhynchtLS Tiirudinaceus, although normally located in the intestine, sometimes perforates the 
 intestinal wall, in which case it may be found in the peritoneal cavity. (See No. 2 of this key, first para- 
 graph.) 
 
 Ascaris suum may be found aberrant in various locations outside the digestive tract. Diagnostic char- 
 acters for the identification of this species have already been given. (See No. 2 of this key, second 
 paragraph.) 
 
 * Included by Von Linstow (1878a) among the parasites of the domestic hog, but its occurrence in this 
 host is questionable.
 
 THE EOUNDWORMS OF DOMESTIC SWINE. 41 
 
 CLASSIFIED LIST OF ROUND WORMS PARASITIC IN DOMESTIC 
 
 SWINE. 
 
 Specific descriptions are omitted from the following list as these 
 have already been given in the key to the roundworms of swine. 
 Arranged according to their respecive orders, families, and genera, 
 the roundworms reported as parasitic in domestic swine are as follows: 
 
 Class Nemathelminthes: Cylindrical worms without a prebuccal ciliary apparatus 
 provided with a variable nervous system, not forming a ventral 
 chain. Generally dioecious. 
 
 Order Nematoda. Nemathelminthes: Provided with a complete digestive tube. 
 Family Angiostomidae. Nematoda: Having two heterogenetic generations, 
 one of free-living males and females and one of hermaphroditic 
 or parthenogenetic forms which are parasitic. 
 
 Genus Strongyloides. Angiostomidse : Parasitic form with mouth 
 opening directly into the relatively very long subcylindrical 
 esophagus. Vulva posterior of the middle of the body. Uterus 
 double. Two ovaries. Free-living form with mouth opening into 
 a vestibule or pharynx, followed by an esophagus whose anterior 
 portion is fusiform and posterior portion globular. 
 
 Strongyloides suis. 
 
 Family Gnathostomidae. Nematoda: Body furnished throughout its length, 
 or only anteriorly, with chitinous blades or wings, serrated posteri- 
 orly. Head subglobular, covered with simple spines. 
 Genus Gnathostoma: With the characteristics of the family. 
 
 Gnathosloma hispidum. 
 
 Family Trichinellidae. Nematoda: Esophagus consisting of a chain of single 
 cells, the lumen of the esophagus passing through the center of 
 each cell. Anterior portion of body containing the esophagus 
 usually very slender; posterior portion containing the intestine 
 and reproductive organs more or less swollen. One testicle, one 
 ovary. 
 
 Subfamily Trichinellinse. Trichinellidae : Male without spicule. Female 
 ovo viviparous. Adulte in intestine of host produce larvae which 
 penetrate into the muscles, become encysted, and develop to 
 maturity when the flesh of this animal is eaten by another animal. 
 Genus Trichinella. Trichinellinse : Very small worms with capillary 
 bodies. Progressively increasing in diameter posteriorly. Male 
 with two conical posterior appendages forming a copulatory bursa. 
 Vulva of the female in the anterior fifth part of the body. 
 
 Trichinella spiralis. 
 
 Subfamily Trichurinse. Trichinellidae: Male with spicule. Female 
 deposits eggs characterized by the presence of an opening at each 
 pole closed by a pluglike operculum. Egga do not hatch until 
 swallowed by a suitable host. Development, so far as is known, 
 direct, without an intermediate host. 
 
 Genus Trichuris. Trichurinae: Anterior portion of body very long 
 and slender. Posterior portion of body containing the intestine 
 and reproductive organs relatively thick and much shorter than 
 the anterior portion. Posterior portion of male rolled dorsally 
 into a spiral. Spicule surrounded by a prepuce-like sheath. 
 Posterior portion of body of female slightly curved. Vulva near 
 the beginning of the posterior portion of body Trichuris suis.
 
 42 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 Family Filariidte. Nematoda: Body long, filiform. Mouth surrounded with 
 papillae, or provided with two lips. Esophagus slender, without 
 posterior bulb. Males with two unequal spicules (sometimes with 
 a single spicule). Females with two ovaries. Vulva usually 
 anterior of the middle of the body. Development often requires 
 an intermediate host. 
 
 Genus Filaria. Filariidae: Body long and slender, of nearly uniform 
 diameter throughout; males considerably smaller than the females, 
 with the tail hooked or curved in a spiral, sometimes furnished 
 with lateral wings. Usually there are four preanal and a variable 
 number of postanal papillae. Spicules usually very different in 
 shape and dimensions. Vulva more or less near the mouth. 
 
 Filaria bauchei. ' 
 
 Genus Setaria. Filariidae: Head armed with a projecting peribuccal 
 circle, deeply notched laterally, somewhat less indented dorso-ven- 
 trally, giving the impression of two teeth when seen laterally and 
 of four teeth when seen at an angle. Tail of both sexes provided 
 with two special appendices Setaria bernardi. 
 
 Genus Gongylonema. Filariidae: Body filiform, slightly attenuated 
 at either end. Anterior portion of body covered with numerous 
 tubercles or shields formed by differentiation of the cuticle. In 
 the median lines immediately behind the mouth, two semilunar 
 depressions, one dorsal, the other ventral. Tail of male curved 
 ventrally, supplied with two asymmetrical membranous wings. 
 Vulva a short distance anterior of the anus. .Gongylonema scutatum. 3 
 
 Gongylonema pulchrum. 
 
 Subfamily Arduenninae. Filariidse: 3 Mouth with two lateral lips leading 
 into a pharynx marked with cuticular ridges in the form of spirals 
 or rings. Spicules unequal, the longer several times the length of 
 the shorter. Four pairs of preanal papillae. Eggs containing 
 embryos at the moment of ovi position. 
 
 Genus Arduenna. Arduenninae: Mouth leading into a cylindrical 
 pharynx marked by ridges, forming a continuous multiple spiral. 
 Esophagus continuous, nearly one- third of the length of the body. 
 Spicules very long and very unequal. Tail twisted in a single 
 coil. Bursa asymmetrical, supported by five pairs of papillae. 
 
 Arduenna strongylina. 
 Arduenna dentata. 
 
 Genus Physocephalus. Arduenninae: Body furnished anteriorly 
 with six lateral wings arranged in a group of three wings each, on 
 either side. The middle wing of each group is the widest. Pharynx 
 cylindrical, relatively broad and long, marked with a simple spiral 
 ridge on the inside, breaking up into separate rings and resuming 
 the spiral at the posterior end Physocephalus sexalatus. 
 
 Genus Simondsia. 4 Filariidae: Female characterized by a tegumen- 
 tary excrescence in the form of a rosette situated in the posterior 
 part of the body and inclosing a prolongation of the intestine and 
 a hypertrophied uterus Simondsia paradoxa. 
 
 i.This species, described by RailHet and Henry (1911), is provisionally included in the genus Filaria, 
 sensu lato. As only one female was received, the material was insufficient for a more accurate generic 
 diagnosis. 
 
 * Sec footnote 2, p. 39. 
 ^ See footnote, p. 9. 
 
 Railliet and Henry (1911b) include Simondsia In the subfamily Arduenninne, although Piana (1897e) 
 describes the lips as dorso-ventral rather than lateral. In the structure of the esophagus, the number 
 of preanal papillae, and the inequality of the spicules Simondsia conforms to the description of the sub- 
 family Arduenninse.
 
 THE ROUNDWORMS OF DOMESTIC SWINE. 43 
 
 Family Strongylidae. Nematoda: Head with eix more or less distinct circu- 
 moral papillae. Males with a more or less well-developed bursa, 
 each lateral lobe of which is usually supplied with six supporting 
 rays. Spicules equal or subequal. Vulva may be anterior to the 
 middle of the body, but is usually posterior. Oviparous. De- 
 velopment, so far as known, direct without intermediate host. 
 Subfamily Strongylinae. Strongylidse: Buccal capsule well developed. 
 Eggs in the process of segmentation at the moment of oviposi- 
 tion. Embryo nearly always rhabditiform and development di- 
 rect. Parasitic in the alimentary canal; exceptionally in the res- 
 piratory system. 
 
 Genus (Esophagostomum. Strongylinae : Head 75 p or more in diam- 
 eter; buccal capsule small. Cuticle surrounding the mouth usually 
 inflated to form a ringlike mouth collar. Bursa of male with two 
 lateral lobes united by a smaller median lobe. Spicules more than 
 0.5mm. long, slender, tubular, pointed ; gubernaculum present, but 
 not conspicuous (Esophagostomum dentatum. 
 
 Genus Globocephalus. Strongylinse: Buccal capsule cylindrical, 
 larger in diameter than the thickness of the body, supported by 
 two chitinous rings one at the anterior end of the capsule, the 
 other at the posterior end. The rings are joined by four chiti- 
 nous longitudinal bands Globocephalus longemucronatus. 
 
 Genus Crassisoma. Strongylinse: Buccal capsule oval, smaller in 
 diameter than the thickness of the body, supported by eight longi- 
 tudinal thickenings of the cuticle, and a chitinous ring on the 
 
 inside of the capsule Crassisoma urosubulatum. 
 
 Subfamily Trichostrongylinse. Strongylidae : Buccal capsule absent or 
 slightly developed. Eggs generally segmenting at the time of 
 oviposition. Embryo rhabditiform and development direct. 
 Parasitic in the alimentary canal. 
 
 Genus. Undetermined Strongylus rubidu*. 
 
 Subfamily Metastrongylinse. Strongylidse : Buccal capsule absent or 
 slightly developed. Eggs in various stages when oviposited. 
 Embryo rhabditiform. Evolution unknown, perhaps requiring an 
 intermediate host. Parasites of the respiratory or circulatory 
 system. 
 
 Genus Metastrongylus. Metastrongylinae: Mouth with six lips. 
 Postero-lateral ray much reduced or absent. Dorsal ray and 
 externo-dorsal rays slender, the others thick. Two very long 
 spicules. Vulva close to the anus. Eggs with well-developed 
 embryos. Parasitic in the bronchi and trachea. 
 
 Metastrongylus apri. 
 
 o , , ., Metastrongylus brevivaginatus. 
 
 bubfamily not determined. 
 
 Genus Stephanurus. Strongylidae: Anterior extremity truncated; 
 mouth suborbicular, limited by a chitinous ring furnished with 
 teeth. Caudal bursa of male with many lobes. 
 
 Stephanurus dentatus. 
 
 1 See footnote 1 on p. 39.
 
 44 THE ROUNDWORMS OF DOMESTIC SWINE. 
 
 Family not determined. 1 
 
 Genus Dioctophyme. Nematoda: Body cylindrical, mouth without 
 lips, surrounded by papillae. Male furnished with a filiform 
 spicule. Female with a single ovary. Vulva in the anterior part 
 
 of the body Dictophyme visceralis. 
 
 Family Ascaridae. Nematoda: One lip median, dorsal; two submedian, 
 ventral. Relatively thick forms. Males provided with two 
 spicules. Females with double ovary. 
 
 Genus Ascaris. Ascaridae: Furnished with three strong lips, the 
 lateral sides of which are generally toothed. Males with two equal 
 or subequal spicules and numerous papillae anterior and posterior 
 of the anus. Vulva located anterior of the middle of the body. 
 Eggs globular or ellipsoidal, usually surrounded by an albu- 
 minous envelope. In process of segmentation at the time of ovi- 
 
 position Ascaris suum. 
 
 Order Acanthocephala. Nemathelminthes without mouth or digestive tube. 
 
 Furnished with a protractile proboscis armed with hooks. 
 Family Gigantorhynchidae. Acanthocephala: Body large and annulated; 
 taeniaform. Hooks of the proboscis with two roots and covered 
 with a transparent layer of chitin. Lemnisci lengthened into the 
 form of rounded bags and having a central canal. 
 Genus Gigantorhynchus; with the characteristics of the family. 
 
 Gigantorhynchus hirudinaceus. 
 
 i Dioctophyme visceralis although commonly included in the family Strongylidse does not conform to all 
 the characteristics of this family. It more closely resembles the Filariidae as pointed out by Raillet and 
 Henry (1909a). Probably it should be placed in a family by itself, but the question is open to further study.
 
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 THE ROUNDWORMS OF DOMESTIC SWINE. 47 
 
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