OSTEOLOGY OF CARNIVOROUS DINOSAURS. O 



indeterminate specimen. Were Allosaurus established on a good and sufficient 

 specimen there might be some reason in maintaining the genus as suggested, but 

 since it also is based on meager materials, that are hardly more diagnostic than the 

 genotype of Antrodemus, it would seem therefore, that the law of priority should 

 prevail. 



I do not feel that the characterization of the genus Allosaurus on the topotype 

 would any more firmly estabhsh it, than if that same specimen were used to define 

 the genus Antrodemus which clearly has priority. The matter of retaining a name 

 because it has become well fixed in the literature has no weight in nomenclatural 

 procedure so long as it can be shown that an already existing name has precedence. 



In view of the fact that such evidence as there is, indicates that in all prob- 

 ability *all of these specimens pertain to a common genus, it would seem inexpe- 

 dient to apply the third proposition to the present problem. Later, with the 

 acquisition of new materials if it is found that two genera have been confused in 

 these fragmentary types, it will then be time enough to adopt the third proposition. 



At this time I propose to consider all of these specimens previously identified 

 as Allosaurus fragilis as pertaining to Antrodemus valens Leidy, and from them 

 have derived the characters which I consider diagnostic of the genus as given below : 



Generic characters: Premaxillaries with 5 teeth; maxillaries with 15 to 17 teeth; 

 dentary with 15 to 16 teeth; 9 cervical vertebrae, opisthocoelus; 14 dorsal vertebrse, 

 amphicoelus; 5 sacrals; distal caudals with elongated prezygophyses; pelvis not coos- 

 sified; pubis with notch funtioning as pubic foramen; 3 digits in manus, first pro- 

 vided with robust curved ungual; third digit reduced; 4 digits in pes, first (hallux) 

 reduced; dermal ossifications not Itnown; abdominal ribs present. 



ANTRODEMUS VALENS Leidy, 1870 



Plates 1-16. 



Poicilopleuron (Antrodemus) valens Leidy, Proc. Acad. Nat. Sci. Phila., 1870, p. 3; Extinct Vert. Fauna 

 West Terr. 1873, pp. 267-279, (Poicilopleuron) pi. 15, figs. 16-18, (Antrodemus).— Meheill, G. P., 

 Bull. No. 53, U. S. Nat. Mus., pt. 2, 1907, p. 76.— Zittel, K. A., Handbuch der Palaeontologie, pt. 

 1, vol. 3, 1890, p. 722. 



Antrodemus valens, Hay, 0. P., Bibliog. and Cat. Foss. Vert. N. Amer. Bull. No. 179, U. S. Geol. Survey, 

 1901, pp. 489, 490.— Nopcsa, F. Baron, Foldtani Kozlony, vol. 31, 1901, p. 199.— Hay, O. P., Proc. 

 U. S. Nat. Mus., vol. 35, 1908, p. 353.— Huene, F. von, Geol. und Paleont. Abhand. Sup. vol. 

 50, 1907-1908, pp. 326, 334.— Zittel, K. A., Grundzuge der Paleontologie, pt. 2, 1911, pp. 280, 282.— 

 Mook, C. C, Annals New York Acad. Sci., vol. 27, 1916, p. 142, (as Antrodesmus valens.) 



Allosaurus fragilis Marsh, O. C, Amer. Jour. Sci., ser. 3, vol. 14, 1877, pp. 515; Amer. Journ. Sci., 

 ser. 3, vol. 27, 1884, pp. 335-337, pis. 11, fig. 2, pi. 12, fig. 2; Sixteenth Ann. Kept. U. S. Geol. Surv., 

 pt. 1, 1896, p. 163, pi. 10, fig. 2; pi. 11, fig. 2; pi. 13, fig. 5 (as Labrosaurus fragilis); Mong. U. S. 

 Geol. Surv., vol. 27, 1897, p. 505, fig. 61; Amer. Journ. Sci., ser. 4, vol. 7, 1899, p. 232, fig. 3.— 

 Lydekker, R. Cat. Foss. Reptilia and Amphibia in British Museum, pt. 1, 1888, p. 154, fig. 25. — 

 Zittel, K. A., Handbuch der Palaeontologie, Abt. 1, vol. 3, 1887-1890, p. 726, fig. 628 (as Allosaurus 

 agilis).— Hutchinson, H. N., Extinct Monsters, 1893, p. 84, text fig. 16.— Hay, O. P., Bull. No. 

 179, U. S. Geol. Survey, 1901, p. 489.— Nopcsa, F. Baron, Foldtani Kozlony, vol. 31, 1901, p. 199.— 

 Williston, S. W. Amer. Journ. Sci., ser. 4, vol. 11, 1901, p. 111.— Zittel, K. A., Text-book of Paleon- 

 tology, Eng. ed., vol. 2, 1902, pp. 229-230, fig. 330 (as Allosaurus agilis).— Osborn, H, F., Bull. 

 Amer. Mus. Nat. Hist., vol. 19, 1903, pp. 697-701, figs. 1, 2; Century Magazine, vol. 68, 1904, pp. 

 680-694.— Beasley, W. A., Sci. American, vol. 97, 1907, pp. 446-447, 3 text figs.— Huene, F. von, 

 Geol. und Palaeont Abhand. Sup., vol. 1, 1907-1908, pp. 326, 327, 334.— Hay, O. P., Proc. U. S. 

 144035°— 20 2 



