o j ^i 2 = 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 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. BIBLIOGRAPHY. DE BLAINVILLE, MARIE HENRI DUCROTAY. 1828a. Vers