21 



This species is distinct from 0. angulatus described by Cope* from the White Elver 

 (Oligocene) beds of north-eastern Colorado. The vertebrae of Cope's species approach more 

 closely in general form those of the Cypress Hills species than do chose of other described 

 species of the genus. 0. arenarum, Douglass,** from the Flint Creek beds (Miocene) of Mon- 

 tana, differs in important particulars. 



OROCODILIA. 



Crooodilus prenasalis ? Loomis. 



Crocodilus prenasalis, Loomis, 190 4. Two new river reptiles from the Titanothere beds ; 

 Amer. Jour. Sci., vol. XVIII, p. 427, figs. 1-9. 



Few crocodilian remains were found in the Oligocene deposits of the Cypress hills in 1904, 

 and none had been secured previous to that date. The writer obtained in 1904 the following 

 specimens: — two vertebral centra, two keeled scutes, a fragment of a pitted bone from the 

 head and a tooth. These specimens were found separately, but probably belong to the same 

 species. 



The vertebras are from the dorsal region. They are concave in front, and prominently 

 convex behind, and in each case the base only of the neural arch remains. One specimen is 

 much smaller than the other, and, probably, belonged to a young individual, as the suture 

 between the neural arch and the centrum is strongly marked. The dermal scutes have 

 numerous deep, rounded pits in the upper surface, are prominently keeled longitudinally, and 

 their margins bear no evidence of having been in contact with other scutes/ The under 

 surface is even and flat. The tooth is elongate conical and curved slightly inward, and back- 

 ward ; its surface is quite smooth. The inner face is defined in front, and behind, by a well 

 developed ridge that extends from near the base to the apex. The base of the tooth is deeply 

 excavated. 



Measurements. 



Large vertebra : — MM. 



Maximum length at mid-height of centrum 35 



Height of anterior articular face 20 6 



Maximum breadth of same . 22 



Height of posterior articular face 18 2 



Maximum breadth of same 17 • 8 



Length of floor of neural canal 28 • 5 



Length of inferior surface 22 • 5 



Small vertebra : — 



Maximum length at mid-height of centrum 25 



Height of anterior articular face 15 



Maximum breadth of same , IS 



Height of posterior articular face 13 



Maximum breadth of same 15 



Length of floor of neural canal IS 



Length of inferior surface • 15 "5 



* Report U. S. Geo] . Survey Terrs,, vol. Ill, Tertiary Vertebrata, book I, 18S4, p. 783. 

 ** Annals of the Carnegie Museum, 1903, vol. II, Art. X, p. 171. 



