NATURAL SCIENCES OF PHILADELPHIA. 39 



much too large for either of the largest existing american cats, 

 the Panther and the Jaguar. It is as much too small to have 

 pertained to the American Lion, Felts atrox, for its breadth is but 

 slightly greater than that contained in the lower jaw from which 

 the latter was described. Breadth of the crown of the tooth is 15^ 

 lines; its thickness in front 8 lines. The measurements in the 

 corresponding teeth of a Bengal Tiger are, 16 lines in breadth, 

 and H lines in thickness in front. The form of the fossil tooth is 

 the same as in the other feline species. 



The extinct species may be named Felis Augustus. 



A distal extremity of a humerus, from the Niobrara River, about 

 the size and construction of the corresponding part in the Bengal 

 Tiger, may belong to this species. 



Another fossil, consisting of a detached body of a vertebra, ap- 

 parently indicates an extinct reptile allied to Plesiosaurus and 

 Discosaurus. The specimen, recently received from Prof. Hayden, 

 was obtained in 1870, on Henry's Fork of Green River, Wyoming. 

 It is free from attached matrix, and was the only specimen pertain- 

 ing to the animal which was found. It probably belonged to a for- 

 mation of earlier date than that of the same locality which has 

 yielded other fossils previously described. 



The vertebra is from the base of the tail, and is much shorter in 

 relation to its other dimensions than in Plesiosaitrus or Discosau- 

 rus. The extremities are concave, and encircled near the margin 

 of the articular surfaces with a narrow groove. Posteriorly there 

 are two large articular facets, as widely separated as the bone 

 would permit, for the junction of a chevron. Anteriorly there are 

 no marks of chevron attachment. The roots of strong transverse 

 processes or diapophyses project from the sides of the body just 

 above the middle. The neural arch was completely co-ossified 

 with the body, leaving no trace of its earlier separation. 



The breadth of the body is 23 lines ; its depth 19 lines, and its 

 length if ,- nch. 



Viewing the specimen as probably representing a genus different 

 from those mentioned, I propose to name it with the species as 

 Oligosimus grand^evus. 



Another fossil is a remarkable specimen, obtained by Prof. 

 Hayden in the " Black Foot country" at the head of the Missouri 

 River. It looks as if it had formed part of the dermal armor of 

 some huge saurian or perhaps of an armadillo-like animal. It is 

 imperfect, and looks as if it were half broken away. In its pre- 

 sent state it is hemiovoid, about two inches in diameter, concave 

 below, and convex above, where it is covered by about fifteen 

 large mammillary bosses. 



Accompanying this specimen there is a distal phalanx, which 

 may belong to the same animal. It is rather less than two inches 

 long. The articular surface is transversely elliptical, 1% inch 

 wide, and 11 lines deep, and feebly depressed, so as to indicate a 



1872.] 





