co nes EAEE 1 , RKS '§ ON THE TYPE OF THE FOSSIL CETACEAN AGOROPHIUS | : PYGM.EUS (M ller) / No, 1694 F WASHINGTON CITY O PUBLISHED BY TH! Oy DOE SMITHSONIAN INS * Sy b 1907 REMARKS ON THE TYPE OF THE FOSSIL CETACEAN AGOROPHIUS PYGMAUS (Miller) BY FREDERICK W. TRUE No, 1694 CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION 1907 Ry, CORNE fy UNIVER GET LIBRARY REMARKS ON THE TYPE OF THE FOSSIL CETACEAN AGOROPHIUS PYGMA:US (Miller). By FREpERICK W. TRUE. (With One Plate.') Somewhat more than fifty years ago the Smithsonian Institution, then recently founded, undertook the publication of a number of memoirs by Prof. Louis Agassiz, and prepared some lithographic plates to accompany them. Before the work had proceeded very far, Professor Agassiz made other arrange- ments for the publication of his writings and the plates were never issued. One of these unpublished plates represents the type-specimen of a very remarkable species of fossil cetacean, now known as Agorophius pygmaeus (Miiller), and on account of circumstances which are detailed below it has been thought desirable to issue it, with a brief explanation as to its importance. In 1847 Prof. F. 8. Holmes and Prof. L. R. Gibbes of Charleston, South Carolina, obtained from the Eocene marl of Ashley river at Greer’s Landing, about 10 miles from the city, an imperfect cetacean skull. The specimen was placed in the hands of Mr. M. Tuomey, Geologist of the State of South Carolina, who published an account of it, with two figures, in the Proceedings of the Phila- delphia Academy of Natural Sciences,’ and also in the Journal of the Academy,* referring it to the genus Zeuglodon (or Basilosaurus). These publications attracted the attention of Prof. J. Miller of Berlin, Ger- many, who was at that time engaged in the study of Zeuglodon (or Basilosaurus), and an account of the specimen, with a copy of Tuomey’s figures, appeared in 1849, in his work on that genus, under the name of Zeuglodon pygmeus.? 1The plate bears the legend ‘‘ Phocodon holmesii Agass.’’, a manuscript name. 2See Toumey’s Report on Geology of South Carolina, 1848, p. 166. *Proc. Acad. Nat. Sci. Phila., 3, 1847, pp. 151-153. ‘Jour. Acad. Nat. Sci. Phila., 1, 1847, pp. 16-17. 5 Zeuglodonten von Nordamerica, 1849, p. 29, pl. 23, figs. 1, 2. 4 TYPE OF THE FOSSIL CETACEAN AGOROPHIUS PYGMAUS Not long afterward the specimen came to the attention of Prof. L. Agassiz, who arranged to have the plate prepared which accompanies this notice." The name “ Phocodon holmesii Agass.” appears to have been placed on the plate when first made. So far as I am aware, it did not appear in print elsewhere until mentioned by Leidy in a list of synonyms of ‘‘ Squalodon pygmeaus” in 1869.’ In 1867 Cope referred the specimen to the genus Dorudon Gibbes (1845), an ally of Basilosaurus,* but in 1868 concluded that it did not belong to the former,’ remarking that it was “ not only generically distinct from Bastlosaurus, but from Doryodon also.” About this time Leidy obtained a loan of the specimen from Professor Holmes, and upon examination of it decided to refer it to Sgualodon, under the name of Squalodon pygmeus. He published an excellent description and two figures of it in his work on the Extinct Mammalian Fauna of Dakota and Nebraska, already cited.* Finally, in 1895, Cope, confirming his earlier opinion that the specimen rep- resented a distinct genus, gave it the name of Agorophius,’ remarking at the same time: “The form of the skull in this genus approaches distinctly that of Cetotherium of the Balenide, and the permanent loss of the teeth would probably render it necessary to refer it to a Mystacocete.” . This idea did not originate with Cope. Paul Gervais wrote in 1871: ‘It is in connection with the rorquals (a la suite des rorquals), and not among the Squalodons, that it is necessary to class Squalodon pygmeus. The form of this skull is quite similar to that of the rorquals, and it differs, on the contrary, from that which characterizes the Squalodons, if one take as an example of the latter the Squalodon of Barie, in the museum of Lyons.’’* As this suggestion is one of great moment, the specimen has a twofold interest and importance—first as representing a very distinct genus, and, second, as representing a possible direct ancestor of the whalebone whales. In view of the excellent character of the figures published by Leidy, it would at first appear that no more were necessary, but a number of considerations led me to recommend that the earlier plate by Professor Agassiz be now pub- lished. Most important of all is the fact that the unique specimen which it portrays appears to have been lost. So far as I have been able to ascertain, it 1“ Phocodon, Agassiz. Prof. A. will soon publish a complete memoir on this genus found in the United States, in which will be given the result of his personal observations drawn from large collections of remains.” (Note by Wyman in Amer. Jour. Sci., 10, 1850, p. 230, foot-note.) 2 Jour. Acad. Nat. Sci. Phila., (2), 7, 1869, p. 420. 3 Proc. Acad. Nat. Sci. Phila., 1867, p. 155. Cope altered the spelling to Doryodon. 4 Ibid., 1868, p. 186. 5 Jour. Acad. Nat. Sci. Phila., (2), 7, 1869, p. 420, pl. 29, figs. 7, 8. ® Proc. Amer. Philos. Soc., 34, 1895, p. 139. TNouv. Archiv. Mus. Hist. Nat. Paris, 7, 1871, p. 138. P16: A Sonrel on stone tromnat: Boston. . : Tappan & Bradford's lithY PHOCODON HOLMESII Agass. TYPE OF THE FOSSIL CETACEAN AGOROPHIUS PYGM AUS 5 has not been seen by any zodlogist since Leidy examined it in 1869, Leidy’s statement at that date’ was as follows: “Professor Holmes, to whom the speci- men now belongs, has recently submitted it to my examination.” The Holmes collection was purchased by the American Museum of N atural History in 187 3, and one would naturally expect to find the skull of Agorophius in that institution, but on writing to Dr. H. C. Bumpus, director, I was disappointed to learn that it could not be found. Thinking that Leidy might have deposited it in the Philadelphia Academy, I wrote to Prof. J. Percy Moore regarding it, but was informed that it was not in the museum of that institution. A comparison of Leidy’s figures with those in the plate now published shows, first, that some fragments of the skull had been lost between 1850 and 1869, and, second, that the single tooth originally remaining in the skull had also disappeared. The principal pieces of the skull lost were a fragment from the proximal end of the right maxilla and a fragment from the distal end of the post-orbital process of the left frontal. In Leidy’s side view of the skull the left premaxilla was transposed to the right side. He did not figure the left side of the skull. The single tooth, already mentioned, which is so well shown in figs. 2, 4. 5, and 6 of the plate published herewith, is not shown at all in Leidy’s figures, and that author remarked that it had been lost. The original figures of the upper surface and right side, published by Tuomey in 1847,* are crude but apparently fairly accurate. The maxillee as there shown are complete proximally, indicating that portions of the skull at this point were lost at some subsequent date. The form of the single tooth is substantially that of the later and more carefully drawn figures. Tuomey states that a portion of the left upper maxilla containing one tooth was found by F. 8. Holmes in the Eocene beds of Ashley River, about 10 miles from Charleston, and that Prof. Lewis R. Gibbes afterward visited the same spot and found the remainder of the skull. He gives the following dimensions: Length (incomplete), 142 in.; greatest breadth, 73 in.; height, 52 in.; length of enameled portion of tooth, % in. In the preceding paragraphs I have mentioned briefly some of the views that have been expressed by zodlogists regarding the relationships of Agorophius. It may be desirable to consider this subject a little more in detail. As regards the opinion that Agorophius is a near ally or possibly a direct ancestor of the rorquals, it appears to me that there is little probability of its correctness. 1Jour. Acad. Nat. Sci. Phila., (2), 7, 1869, p. 421. ; ; ?Proc. Acad. Nat. Sci. Phila., 3, 1847, pp. 15J-153. Also in Amer. Jour. of Sci., (2), 4, 1847, pp. 283-5, with copies of the original figures. 6 TYPE OF THE FOSSIL CETACEAN AGOROPHIUS PYGMZUS While it is true that both the rorquals and Agorophius have large and wide temporal fossee and a compressed vertex, these are, I think, only superficial resemblances. In all existing rorquals (Balenoptera, Megaptera and the aberrant Rhachianectes) the orbital processes of the frontals are pushed backward toward the brain-case, and are scarcely covered at all anteriorly by the maxilla. In Agorophius the frontals are almost entirely covered by the maxille and a wide space intervenes between them and the brain-case. In Agorophius again the median constriction at the vertex is formed by the parietals, while in the rorquals it is formed, superiorly at least, by the frontals, which meet the supra- occipital and exclude the parietals from the top of the skull. In the Tertiary rorquals, Heterocetus, Mesocetus, Idiocetus, Aulocetus, etc., in which the parietals appear on the vertex for some distance, the relations of the frontals and maxille are not substantially different from those found in existing genera, and show no closer approximation, so far as I can see, to the relations of these bones in Agorophius. The ancestor of the rorquals and other whalebone whales was, in my opinion, a very different form from