1880.") DENTAL CHARACTERS OF THE CANID^E. 245 



the interorbital and the temporal regions of the skull. In Cams 

 azarce the temporal ridge is not so well marked ; and, beginning to 

 diverge from its fellow a little in front of the coronal suture, it passes 

 with a very slight curve to the angle of the supraorbital process, 

 while the postorbital constriction is small (fig. 1, A). Moreover 

 there is hardly any depression on the upper surface of the supra- 

 orbital process, the whole glabellar region being evenly arched from 

 side to side. In the Fox, there is a well-marked depression on the 

 outer part of the upper surface of the supraorbital process, and the 

 glabella is flatter. These external differences answer to small but 

 very definite distinctions which are seen in the longitudinal sections. 



The superimposed sections of the two skulls correspond almost 

 exactly. 



In C. vulpes, as in all the Canidse, the cribriform plate of the 

 ethmoid bone is funnel-shaped, the concavity being turned towards 

 the cranial cavity, while the convex surface looks outwards and up- 

 wards above, outwards and downwards below, into the nasal cham- 

 ber. From its outer surface the delicate rolled laminae of bone 

 which answer to the superior and middle turbinals of human 

 anatomy take their origin. The lower plates project backwards as 

 far as the ethmo-praesphenoidal suture ; while the upper ones reach 

 as far back as the junction of the ethmoid with the frontal bones, 

 and are covered over by the orbital and nasal prolongations of those 

 bones. In C. vulpes, however, there are no frontal sinuses ; that 

 is to say, behind the point of union with the ethmoid the median 

 parts of the thin frontal bones are solid throughout. Moreover, 

 if, as in man, we distinguish that part of the frontal bone which 

 covers the anterior surface of the cerebral hemispheres, from that 

 part which lies further back, as the forehead, then the forehead of 

 the Fox is very short, while the vertical height of the ethmoid is 

 proportionally great. In Canis azarce there is a marked difference 

 in all these respects (fig. 4, A,/, p. 246). A large frontal sinus is 

 developed in each frontal bone, above and behind the fronto-ethmoidal 

 suture. The forehead is much longer, while the height of the 

 ethmoid is less. 



In both skulls a well-defined ridge (fig. 4, a) answers to the 

 supraorbital sulcus, and marks off the region occupied by the curved 

 lateral gyri from that of the orbital and frontal gyri of the brain. 

 But in the Fox this ridge (fig. 4, B, a) is directed upwards and for- 

 wards, and its dorsal end is separated by but a small distance from 

 the dorsal margin of the cribriform plate of the ethmoid ; while in 

 Canis azarcE the dorsal half of the ridge (fig. 4, A, a) is inclined 

 slightly backwards, and its end is far more remote from the edge of 

 the cribriform plate. Moreover the inner wall of the skull is 

 much more sharply bent inwards along the dorsal half of the orbito- 

 frontal ridge than it is in the Fox. 



These differences have their counterparts in the form of the brain, 

 and become very manifest when casts of the interior of the skull are 

 compared (fig. 5, p. 247). In the Fox the contour of the brain, viewed 

 from above, is that of a pear with the narrow end forwards. Late- 



