THE HEAD. 87 



Horse ; for in eight the average relation between the length and width was r25, 

 instead of 1"24 — a difference not very great, certainly. The difference becomes 

 more marked, however, between the Ass and Horse, if the length of the cerebral 

 be compared with that of the cerebellar cavity. This comparison has yielded an 

 average of r962 in the Horse, and r927 in the Ass — which proves that the 

 cerebellar cranium is longer in the Ass than the Horse. 



The cranium is, as it were, strangled behind the orbital processes of the 

 frontal bones. In glancing at the cranium of the Horse and Ass, it would at first 

 appear that that of the Ass is relatively naiTOwer than the cranium of the Horse. 

 We have measured six heads of each species for the width of the cranium at its 

 greatest diameter, behind the orbital processes, and, in comparing these two 

 diameters, have obtained the following results : in the Horse, the relation varied 

 between ri8 and l"21 ; in the Ass, between r20 and r47. The average has 

 been, for the Horse, r226, and r335 for the Ass. From these figures, it might 

 be concluded that the cranium of the Ass is relatively more constricted at its 

 inferior extremity than that of the Horse. In the hybrids of the Horse and 

 Ass, the cranial cavity is more elongated, and in this respect the Hinny more 

 resembles the Ass than the Horse. With regard to narrowness of the cranium 

 behind the orbital processes, the 3hih holds the middle place between its parents, 

 while the Hinny comes nearest to the Ass — the reverse of what is noticed 

 in the development of the cerebellar cranium. 



In Ruminants, the shape of the cranium is more or less masked by the 

 frontal or parietal sinuses ; consequently, it is difficult to study satisfactorily this 

 part of the head, particularly in the bovine species. 



The cranium of the domestic Dog offers great varieties ; for the creation of 

 numerous breeds has brought about important differences in the form and 

 dimensions of this part, which it is impossible to deal with here. 



3. Relations between the Cranium and Face. 



Instead of studying the cranium alone, we may compare it with the face in 

 regard to width, length, and the area that each of these two regions occupies in 

 a vertical and median section. We may also, in measuring the facial angle, form 

 an idea of the manner in which these two regions unite to form the head. 



1. The forehead, properly speaking, measured from the union of the parietal 

 crests to the fronto-nasal suture, is always, in the Horse, longer than the cerebral 

 cranium, the second to the first being as 1 : 1-425. The forehead of the Ass is 

 proportionately less developed, for we have found that the cranium is to the 

 forehead as 1 : r265. 



2. This shortness of the Ass's forehead, which renders the head heavy, is 

 corrected by its narrowness ; the head enlarges at the orbital processes. In com- 

 paring the distance between the supra-orbital foramina and the transverse 

 diameter of the cerebral cavity, it has been noted that the width of the cranium 

 is to the space between these foramina as 1 : 1*454 in the Horse, and 1 : 1 '2 65 in 

 the Ass. The forehead of the Ass is, therefore, in proportion to the cranium, 

 shorter and narrower than in the horse. From this point of view, the heads of 

 the Mule and Hinny are intermediate to those of their parents ; but the first of 

 these hybrids is nearer the Horse, and the second approaches the Ass. 



3. Cuvier imagined that one of the means of judging of the intelligence ot 

 animals, would be to compare the area of the craniiun with that of the face, 

 measured on a median section of the head, deprived of the lower jaw. This 



