G. I. Adams — Extinct Felidce of North America. 433 



with Machazrodus as a synonym, but retained Smilodon as a 

 distinct genus (Extinct Cats of North America, Amer. Nat., 

 1880). 



It has not been definitely shown as yet that there are any 

 representatives of the genus Machcerodus in North America. 

 In the American Naturalist, 1887, Cope proposed M. catacopis 

 on the anterior portion of a mandible having a moderate flange 

 and containing the roots of the incisors and a canine with a 

 posterior denticulate border. It is not distinguishable from 

 Hoplophoneus however. Cragin in Science, 1892, proposed M. 

 crassidens on feline remains from the same beds and Williston 

 has since (Kansas University Quarterly, 1895) referred other 

 bones from the same locality to this species. None of the 

 species can be said to be established as belonging to the genus 

 Machcerodus since the generic characters of dental formula, 

 structure of the molar series and the basi-cranial foramina are 

 not determinable in the specimens thus far found in the Loup 

 Fork. _ 



Smilodon is distinctively an American genus. It was estab- 

 lished by Lund, 1842, on a specimen from Brazil (S. neogaens 

 K. Danske Yid. Selsk. Copenhagen). Leidy described a frag- 

 ment of a maxilla containing a sectorial under the name 

 Trucifelisfatalis. In structure the tooth agrees with Smilo- 

 don and a second specimen induced Cope to refer it to that 

 genus. Smilodon jloridanus Leidy is known from a well pre- 

 served skull from which the teeth have been lost. 



The genus Eusmilus was established by Gervais (E. jperar- 

 matus, Journal de Zoologie, 1875). Previously Filhol had 

 described M. bidentatus, which is synonymous, consequently 

 Gervais genus and Filhols species are accepted. 



Dinobastis Cope, although founded on very limited material, 

 will probably prove to represent the latest development of the 

 Machserodont type in North America. The genus is based 

 upon the absence of the internal root of the superior sectorial. 



The genus Dinictis has remained well defined since first 

 proposed by Leidy. To it, however, should be referred the 

 two species of Pogonodon described by Cope. The genus 

 Pogonodon as proposed by Cope does not differ from Dinictis 

 as regards tooth structure, and the absence of the second 

 inferior molar, which in Dinictis is much reduced, is not suffi- 

 cient grounds for retaining it as a distinct genus, since in several 

 specimens of Dinictis it is variable in size and in one is absent 

 from one side. The genus Dinictis as thus constituted shows 

 the reduction of this tooth, just as Hoplophoneus shows the 

 reduction of the superior premolar. 



The genus Hoplophoneus proposed by Cope embraces, besides 

 new species, others previously described under the generic 



B9BHH 



