1919] Merriam: Tertiary Mammalian Faunas of Mohave Desert 537 



molars of the Kicardo specimen, no. 21507, are large and heavy and 

 must have opposed a well developed crushing area on the heel of M 1 

 and on the tubercular lower molars. It may be that C.t ursinus and 

 the Ricardo form are related or it is possible that, as Matthew 39 has 

 suggested, C. ursmus is really an Amphlcyon. It is improbable that 

 the Ricardo form is an Amphlcyon. Though M 2 is a large tooth the 

 form of the maxillary posterior to M 2 makes the presence of a M 3 

 improbable. 



AELUKODON '?, possibly APHOBUS, n. sp. 



A large lower jaw, no. 22470 (fig. 145), represents an Aelurodon- 

 like canid from locality 2769 in the upper portion of the Ricardo 



Fig. 145. Aelurodon?, possibly aphdbus, n. sp. Mandible, no. 22470, X 

 Ricardo Pliocene, Mohave Desert, California. 



beds. This specimen includes the greater part of the mandible with 

 P 4 , Mj, and M 2 , the teeth being badly worn and imperfect. 



The lower jaw is short, heavy, and the inferior side below the 

 posterior end of the molar series is markedly convex. The teeth are 

 massive and thick transversely. The heel of M 1 is short and wide. 

 M, is considerably longer anteroposteriorly than the heel of M 1 . 



The size and proportions of the dentition of specimen no. 22470 

 suggest those of Aelurodon ? aphobus and it is not impossible that this 

 mandible represents an animal of the same type, possibly of the same 

 species. 



The Ricardo jaw resembles Canist ursinus Cope to some extent in 

 massiveness of jaw and dentition, but the mandible may differ in 

 proportions and the tooth proportions are quite different. In C.f 

 ursinus the masseteric fossa extends forward to a point below the 



39 Matthew, W. D., Bull. Am. Mus. Nat. Hist., vol. 16, p. 130, 1902. 



