1879.] 



NATURAL SCIENCES OF PHILADELPHIA. 



177 



heel of the sectorial is well developed. The tubercular is very 

 small. 



The form of the skull is short and wide ; the zygomata are 

 much expanded, and the profile is very convex. The muzzle is 

 short, and the orbits are rather larsfe. The interorbital region is 

 wide and convex, and the postorbital processes are robust, acu- 

 minate, and directed downwards. The infra-orbital foramen is 

 very large. The apices of the premaxillary bones are elongate, 

 but do not reach the frontals. The nasals are rounded posteriorly. 

 The sagittal crest is prominent, and the inion elevated. The 

 posttympanic process is short, and the paroccipital is short and 

 is directed backwards. The cranium is constricted behind the 

 orbits. The mandibular ramus is low posteriorly, and the ante- 

 rior inferior flange is well-developed, but not large. 



Measurements. M. 



Length of skull on base 140 



Width of skull, measured below . . . . .111 



Length of palate 060 



Width of palate between posterior angles of sec- 

 torials 062 



Width of palate between canines .... .020 

 Length of skull to front of orbits (axial) . . .050 

 Vertical diameter of orbit ..... .031 



Intei-orbital width (least) 045 



Elevation of inion from foramen 032 



Length of inferior molar series 050 



Length of inferior sectorial 018 



Length of base of inferior first premolar . . .055 



Depth of ramus at sectorial 016 



Depth of ramus at first premolar .... .021 



Depth of ramus at flange 026 



From the Truckee beds of John Day River, Or* 



egon. 



CANID.E. 



The range of variation presented by the species of Canidse in- 

 cludes several generic divisions, recent and extinct. These genera 

 are, however, as closely intergraded as are those of the cats, and 

 their definite characters are subject to occasional failure from ab- 



