EXTINCT MAMMALIA OF NORTH AMERICA. 431 



same depth, and a length of one inch and a quarter below and one inch at the side. 

 The articular surfaces are moderately concave. The breadth of the spinal canal be- 

 tween the abutments of the neural arch is one inch and seven lines. The roots of 

 the transverse processes project from the lower part of the sides of the body. 



Another cervical vei'tebra, from the eocene formation of Alabama, presented to the 

 Academy by Dr. Clanton, has nearly the same construction as the former, but is 

 larger and more biconcave. The breadth of the body is four inches, the depth three 

 inches, and the length below an inch and a half. The width of the spinal canal is 

 two inches. The stout roots of the transverse processes project from the lower part 

 of the body obliquely. 



CETOPHIS. 



Cetophis heteroclitus. 



Cope : Proc. Ac. Nat. Sc. 1868, 185. 



Founded on caudal vertebrae from the miocene of Charles Co., Maryland. 



SAUROCETUS. 



Saurocetus Gibbesii. 



Agassiz : Proc. Ac. Nat. Sc. 1848, 4. 

 Saurocetus, Gibbes : Ibidem, 57. 



Founded on a tooth from the eocene of South Carolina. 



CETACBA.* 

 DELPHINIDJE. 



DELPHINUS. 



Delphiuus occiduus. 



Leidy: Proc. Ac. Nat. Sc. 1868, 197. 



An extinct speeies is indicated by a fossil derived from the upper miocene formation 

 of Half-moon Bay, California, submitted to my examination by Prof. J. D. Whitney. 

 The specimen consists of an intermediate portion of the upper jaw, devoid of teeth, 

 and encrusted with selenite. It measures along the more perfect lateral border five 

 inches, and in this extent is occupied with nineteen closely set, circular alveoli, rather 

 over two lines in diameter. At the back of the fragment the jaw has measured a 

 little more than two inches wide. From this position it gradually tapers for half its 

 length, and then proceeds with parallel sides to the fore end, where it is ten and one- 

 half lines wide. The palate behind is nearly plane or slightly convex; at its fore 



* Most of the Cetaceans indicated in the present synopsis are accepted on the authority of Prof. Cope, who 

 has devoted much attention to the study of the order. With few exceptions, I have not yet had time nor 

 opportunity to review the materials of his researches. 



