250 



PROF. HUXLEY ON THE CRANIAL AND 



[Apr. 6, 



In this series ^^ and j;;-^, as before, increase out of proportion 

 to the rest, and -^^^ undergoes the least alteration ; but the upper 

 sectorial increases rather more than the lower, which is the reverse 

 of the relation which obtains in the Alopecoid series. 



5, In all young canine animals, the upper edges of the attach- 

 ments of the temporal muscles are separated by a wide interspace of 

 a lyrate form, with its apex directed posteriorly, which may be called 

 the sagittal area. The boundaries of this area are but little raised ; 

 and, as age advances, it becomes gradually diminished by the approxi- 

 mation of the temporal muscles. This approximation takes place 



Fig. 7. 



iNat.Size 



Upper (A) and lower (B) cheek-teeth of C. lupus, half the natural size ; upper 

 (A') and lower (B') teeth of C. asarm (a), of the natural size. The first 

 upper molars are thus brought to the same length, and the proportional 

 increase of size of the sectorial teeth of the Wolf is apparent. 



more rapidly behind than in front, and results in the narrowing, and 

 in most cases coalescence, of the temporal ridges throughout the 

 greater part of the length of the sagittal suture, while in front they 

 diverge to the supraorbital processes and inclose the glabellar area. 



In the smaller Alopecoids, such as C. zerda, the temporal ridges 

 remain permanently separate, and inclose a wide lyrate sagittal 

 area, the ridges themselves not being very strongly marked ; but in 

 C. littoralis and C. cinereo-argentatus (=C. virginianus) the ridges 

 take the form of strongly-raised cord-like elevations, which impart a 

 very characteristic aspect to the skull (fig. 8, p. 251). In this case 

 there is no sagittal crest. But sometimes there is a well-defined 

 though comparatively narrow sagittal area, from the centre of which 

 a low sagittal crest rises. This is well seen in some Jackals, and 

 especially in C. antarcticus. 



