84 GUIDE TO THE FOSSIL MAMMALS AND BIRDS. 



i A ^-^ggi , B 



Fig. 80. — Upper and lower jaws of American Jurassic Multituberculata, 

 from Wyoming, U.S.A. ; three to six times nat. size, as marked. 

 Named by 0. 0. Marsh as follows : — A-c. Ctenacodon potens ; e, f. 

 Ctenacodon serratus ; a, h, i, k, n. Allodon fortis; j, m. Allodon 

 laticeps ; d, l. incisors of Ctenacodon. In upper jaws : — 1, 2, 3, 

 incisors ; a', first premolar ; a", second premolar ; 6, fourth premolar ; 

 6', third premolar; c, second true molar; m, malar arch; s, suture 

 with maxilla. In lower jaws : — a, incisor ; 6, condyle ; c, coronoid 

 process ; r, root of incisor. 



