188jO.J dental characters of the canid^. 239 



number in Otocyon, and to the diminution of the number in Cyon and 

 leticyon. The variation in size of the poUex and its disappearance 

 in Lycaon are well known. The differences in the form of the pupil 

 have been noted ; and, of late, particular notice has been taken of 

 the extensive modifications in the form of the caecum. "Weight has 

 been attached to the presence or absence of a caudal gland. 



The taxonomic value of these variations, however, has remained 

 doubtful. That of the proportional lengths of the nasal bones, for 

 example, is justly disputed by Wagner ', Satisfactory evidence of the 

 form of the pupil is hard to obtain, and does not appear to have any 

 definite correlation with diurnal or nocturnal habits. The presence or 

 absence of a caudal gland has been investigated in only a few species ; 

 and as it occurs in Wolves, Dogs, Jackals", and Foxes, it is not 

 likely to be of much importance. The proportions of the sectorial 

 to the following teeth may be similar in Canidse which are certainly 

 not closely allied, and different in those which are. And the system 

 of measurement hitherto usually adopted gives the absolute sizes 

 of the teeth and their dimensions relatively to one another, but 

 affords no clue to their j)roportions in relation to the size of the 

 skull, or to the increase or diminution of individual teeth. The 

 increase of the number of the teeth of Otocyon appears generally 

 to be regarded merely as an anomaly. 



There can be no doubt that the skulls and the teeth of the Canidse 

 vary from species to species more than any other part of their 

 organization. One has only to put side by side with one another 

 the skeleton of an Otocyon and that of a Wolf or that of a Fox, to 

 see that the cranial and dental differences are very much greater than 

 any which are observable elsewhere ; and a glance at the skull and 

 teeth of any other canine animal is suflScient to show that its cha- 

 racters give it a place somewhere between the former and the two 

 latter. The problem therefore is how to give definite expression 

 to the differences between Otocyon, Fox, and Wolf, and to deter- 

 mine by something better than vague eye-judgments the relation of 

 the other forms to these. 



2. When occupied with anthropological questions, a good many 

 years ago ^ I was confronted by the same kind of difficulty in en- 

 deavouring to arrive at an exact conception of the morphological 

 relations of the skulls of the different races of mankind ; and I was 

 led to adopt a method of estimating cranial characters which still 

 commends itself to me as that which is best calculated to meet the 

 end in view. 



Every constituent of the skull, like all other parts of the body, 

 varies from individual to individual, and from youth to age. But 

 the central region of the base of the skull, formed by the basi- 

 occipital, basisphenoid, and prsesphenoid bones, represents the foun- 



^ Schreber's Saugethiere, Suppl. Bd. ii. pp. 365, 384, notes. 



2 I have found a small caudal gland in a female C. mesomelas, which recentlj' 

 died in the Gardens. 



' " On two widely contrasted Forms of the Human Cranium," Journal of 

 Anatomy, 1867. 



Prog. Zool. Soc— 1880, No. XVI. 16 



