276 PROF. HUXLEY ON THE CRANIAL AND [ApV. 6, 



In iioi:e of these skulls was a trace either of the hinderniost lower 

 molar or of its alveolus to be seen. Jerdon states that C. priniavus 

 " is common in Ceylon, where it is called the Dhole by some, by 

 which name it has been treated of by Hamilton Smith and other 

 writers ; and it is found all over the jungles of Assam, Burmah, and 

 the Malayan peninsula," which is in contradiction to the com- 

 monly received opinion that there are no wild dogs in Assam and 

 Burmah. According to S. Miiller, the same species is found in 

 Borneo. 



The distribution of this group over an area which covers nearly 

 60 degrees of latitude and about as niuch of longitude in Eastern 

 and Southern Asia is very remarkable, when taken in conjunction 

 with the fact that the proper Jackals, although coexistent with Cyon 

 in Hindostan, are absent over the rest of the C7/o?i area, except per- 

 haps in Burmah ; while, to the westward of Hindostan, Cj/on, so 

 far as is known, is absent in the vast area inhabited by the Jackals. 

 For the species united under Cyon appear to me to be nothing but 

 large and slightly modified forms of the Jackal type, which thus 

 sefems to have become somewhat specialized at the eastern extre- 

 mity of its area of distribution. 



I have already referred to the variability of Canis aureus ; and 

 the' amount of variation exhibited by that species will become still 

 more apparent by an inspection of the following Table of measure- 

 ments of the skulls of thirteen specimens of Canis aureus from India. 

 From this it appears that the skull of this species may vary in abso- 

 lute length 28 per cent., in the length of the palate by nearly 30 per 

 cent., in its width by more than 25 per cent., in the length of the 

 basicranial axis by about 20 per cent., in the length of ^^^^ rather 

 more than 25 per cent., in the length of ^-^^ about 1 1 per cent. 



If the measurements of C. anthus, C. lateralis, C. simensis, and 

 C. mesomelas, given in the same table, are compared with those of 

 C. aureus, it is obvious that the great majority fall into place some- 

 where in the series of C. aureus ; and the only notable difference is 

 in C. simensis, in which there is a remarkable elongation of the 

 palate. But this is exactly that part of the skull which varies most 

 in C. aureus ; and the difference in length between the longest and 

 shortest palate in this species, 1 9 millims., is exactly the same as 

 that between the longest palate of C. aureus and that of C. simensis. 

 I do not doubt that a larger number of specimens of C. anthus and 

 of C. simensis would afford a complete series of intermediate forms 

 between them and the Common Jackals. 



Just as, at the eastern extremity of the Jackal area, the large C;/o)i- 

 form with specially modified dentition is met with, so at its western 

 extremity, in South Africa, the large Lycaon-iorm, with specially 

 modified fore feet, occurs. In the breadth of the prsemolar region 

 of the upper jaw, and in a more or less marked convexity of the facial 

 contour, Lycaon strongly reminds one of Cyon ; but the dentition is 

 complete, stronger, and more wolf-like, and the edges of the hinder 

 preemolars are more deeply lobed. 



