﻿CANIS. 11 



exoccipital in contact with it, while they agree with the Arctoiclea in the almost 

 complete absence of a septum dividing the auditory bulla, in the large size of 

 the glenoid foramen, and in the presence of an alisphenoid canal. In the living 

 forms there is no entepicondylar foramen. The upper molars have a triangular 

 crown, and the blade of the upper carnassial consists of two lobes. 



a. The Skull (Plates I— IV). 



The cranium is moderately elongated, the jaws long, tapering, and somewhat 

 compressed. The zygomatic processes of the frontal and malar are short, so that 

 the orbit communicates widely with the temporal fossa. The pterygoid has a well- 

 developed hamular process. The auditory meatus forms a short but fairly promi- 

 nent bony tube. 



The following are characters upon which most stress has been laid in attempt- 

 ing to discriminate between the skulls of wolves, dogs and foxes : 



(1) The relative proportions of the jaws and cranium; 



(2) The extent to which the temporal ridges, always widely separate in young 

 animals, approach and coalesce into a sagittal crest in the adult ; 



(3) The greater or less backward extension of the nasals ; 

 (I) The character of the post-orbital process of the frontal ; 



(5) The union of the nasal processes of the frontals with the ascending pro- 

 cesses of the premaxillse, or the separation of these processes from one another by 

 the meeting of the maxillae and nasals ; 



(6) The length of pm. 4 as compared with that of m. 1 and 2 taken together; 



(7) The orbito-frontal angle or the obliquity of the opening of the orbit to the 

 brow. 



b. Dentition (Plate V). 



(1) Distinctive Features of the Teeth in the Genus Canis. — The typical dental 

 formula is i. f , c. T , pm. f , m. f , as in TJrsus, but in aberrant forms {Cijon) the 

 molars are |, and in a fossil form, Canis (Lycorus) nemesianus, the premolars are f . 

 Further, in Canis cancrivorus the missing last upper molar is occasionally present. 

 The formula embracing these variations is i. f, c. T , pm. ^y, m. §E§. 



The contrast in size between the canine and incisor teeth is not so great as in 

 either cats or bears. The upper carnassial tooth, pm. 4, differs from that in bears, 

 and resembles that in cats and hyasnas in possessing an antero-internally placed 

 inner tubercle supported by a distinct root. 



In accordance with the method adopted in previous memoirs it has been 



