466 University of California Publications in Geology [Vol. ll 



The larger part of a mandible with imperfect dentition, no. 21231 

 (fig. 11), shows a form in which the mandible is thick inferiorly, but 

 thinner above than in the common Aelurodon of the Barstow fauna. 

 M 2 is considerably larger than in the common form. This species 

 resembles the typical Aelurodon wheelerianus in many ways, and the 

 distinctive characters of the specimen may be due merely to individual 

 variation, or they may indicate a species distinct from that repre- 



sented by no. 19398. 



Measurements of no. 21231. 



Length, anterior side of inferior canine to posterior side 98 mm. 



Length of lower premolar series a52 



Inferior canine, anteroposterior diameter at base o24.7 



P 3 , anteroposterior diameter al3 



M,, anteroposterior diameter 25.8 



M,, transverse diameter 11.9 



M 2 , anteroposterior diameter ol3 



M», transverse diameter 8.3 



a, approximate. 



AELUKODON, DINOCYON, or AMPHICYON, sp. 



A portion of a very large, much-weathered lower jaw, no. 21224, 

 with the base of the canine represents a form much larger than 

 Aelurodon wheelerianus. It may represent an Aelurodon, an Amphi- 

 cyon, or a Dinocyon species. The space for incisors is small. The 

 alveolus for P x is very small. 



CANID SKELETAL ELEMENTS, indet. 



A number of scattered skeletal elements representing forms of the 

 canid type have been obtained in the Barstow. Noteworthy among the 

 canid skeletal remains are a number of phalangeal elements which are 

 considerably heavier than those of the typical wolves. A second and 

 fifth metapodial of the anterior extremities (figs. 12a, 12&) represent 

 this type. The short-headed, heavy-jawed tephrocyons and aelurodons 

 of the Barstow fauna were presumably heavy-limbed, and it may be 

 that the specimens before us represent one of these forms. 



A humerus (no. 19468, fig. 13) from the Barstow shows in general 

 the characters of this element in the canids, but is distinguished by 

 the presence of an entepicondylar foramen. 



A small, long-necked astragalus (no. 19469, fig. 14) resembles an 

 astragalus from the Middle Miocene of Virgin Valley, and is possible 

 with the Virgin Valley form to be referred to Tephrocyon. 



A complete tibia and the distal end of a femur of the same animal 

 represent a eanid form presumably about as large as a coyote. The 



