178 BULLETIN UNITED STATES GEOLOGICAL SURVEY. Wol.YI. 



tain to tlie latter genus, with few exceptions. The characters of the 

 genera are as follows : 



I. Molar formula i f . 



Humerus with eiiitrochlear foramen Amphicyon. 



II. Molar formula ^ f . 



Humerus with epitrochlear foramen. 



Inferior sectorial heel trenchant Temnocyon. 



Inferior sectorial heel basin-shaped Galecynus. 



Humerus without epitrochlear foramen. 



Inferior sectorial heel basin-shaped Canis. 



III. Molar formula f p| . 



Heel of inferior sectorial trenchant Enhydrocyon. 



IV. Molar formula | ^. 



Heel of inferior molar basin-shaped Icticyon. 



V. Molar formula ^ \. 



First inferior molar two-rooted Hycenocyon. 



To these genera I refer nineteen species of the American Miocenes. 

 Amphicyon Lartet. 



Bulletin Soci^t^ G6ologique de la France, 1836, vii, 217-220; Blainville, 

 Comptes-Rendus, 1837, v, 434 ; L'Institut, 1837, v, 18-19 ; Blainville, Osteo- 

 f^raphie, ix, Subursus, 78-96. 



Dental formula : I. f ; 0. i ; Pm. f ; M. f . The true molars of the su- 

 perior series all tubercular ; the last two of the inferior series also tuber- 

 cular. First inferior true molar a sectorial, with an internal tubercle 

 and a heel with a superior groove, bounded by raised borders. Hu- 

 merus with an epitrochlear arterial foramen. 



Much is yet to be desired in the elucidation of the characters of this 

 genus, especially of the American forms, which are less abundant and 

 of smaller size than those of Europe. The typical species, Amphicyon 

 major Blv. was the largest, equalling a bear iu size. It is derived from 

 the Miocene of Sansan, and a smaller form of it is found, according 

 to Pomel, at San Gerand-le-Puy. Other species are derived from the 

 latter locality, and all are typical of the Miocene formation in Europe. 

 In the "Mio-plioceue" of India a single species has been discovered, the 

 A. palmndicus of Lydekker. Three species occur in the Lower and Mid- 

 dle Miocene of North America, the largest of which about equals the 

 wolf in size. On account of the large development of the inferior tuber- 

 cular teeth, I have suspected that the Canis ursinus Cope, from the 

 Loup Fork group of New Mexico, would prove to be an Amphicyon. If 

 so, it is the only representative of this genus in our Upper Miocene. 



The three American species differ as follows : The A. cusjpigerus is 

 small, not exceeding the kit-fox in dimensions. The A. hartshornianus 

 is about the size of the coyote, and has rather small tubercular molars, 

 especially of the lower series. The A. vetus is a little larger, but has 

 the tubercular molars disproportionately larger than those of the A. 

 hartshornianus. 



