84 GUIDE TO THE FOSSIL MAMMALS AXD BIRDS. 



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

 from Wj-oming, U.S.A. ; three to six times nat. size, as marked. 

 Named by 0. C. Marsh as follows : — a-c. Ctenacodon ])otens ; E, F. 

 Ctenacodon serratus ; g, h, i, k, k. Allodon fortis ; j. m. Allodcm 

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

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

 b', third premolar ; c, second true molar ; vi, malar arch ; s, suture 

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

 process ; r, root of incisor. 



