264 PROF. HUXLEY ON THE CRANIAL AND [Ap'"' 6» 



Didelphia and Oniithodelphia ', and other indications of the approxi- 

 mation of the lower Carnivores to the Didelphia are not wanting. 



If the mandibles of Otocyon, of Procyon, and of Perameles are 

 viewed from behind (fig. 14, p. 263), it will be seen that the angular 

 process is as distinctly inflected in the two former as in the latter, and 

 that the difference in the angular process of Thylacinus is merely one 

 of the degree of development of a homologous and similarly formed 

 part". 



1 look upon the four molars of Otocyon as another character of 

 the safne order ; as a survival, in fact, of a condition of the dentition 

 exhibited by the common ancestors of the existing Canidse and the 

 existing carnivorous marsupials. 



12. The geographical distribution of the Canidae presents many 

 points of interest when it is considered in relation to the morpho- 

 logical characters of the forms at present restricted to certain areas of 

 the earth's surface. 



Otocyon occurs only in South Africa, and apparently does not 

 range beyond the southern extremity of that continent. 



The niicrodont Alopecoids with lobate jaws(C. cinereo-argentatus 

 and C. Uttoralis), which have been separated by Baird under the name 

 of Urocyon, appear to me to be the nearest existing allies of Otocyon. 

 But there is no representative of this group outside the North- 

 American continent, C. cinereo-ai-gentatus occupying the central 

 States of North America, while C. Uttoralis occurs on the N.W. in 

 California, and on the south as far as Honduras and Costa Rica. 

 Baird suggests that C Uttoralis is merely a local race of C. cinereo- 

 argentatus; and the measurements in Table XII., which show that 

 No. II. is as near to No. III. as to No. I., lend strong support to 

 this view. 



The small Foxes of the Old World, C. zerda and C caama, differ 

 from the foregoing in little more than the nonlohaiion of the man- 

 dible and the less prominent or cord-like character of the temporal 

 ridges. In C. bengalensis, C. corsac, and C. velox the sagittal area 

 narrows and the temporal ridges unite behind, while the sectorial 

 teeth increase in proportional size, and thus gradually lead to the 

 most speciahzed Foxes of the Old World. 



This is shown very clearly by the following table of measurements 

 of thirteen specimens belonging to twelve species of Alopecoids. 



' Proceedings of the Roval Society, 1879. I Lave recently foimd the epipubis 

 very well developed in a female Bengal Fox and in a female C. mesomelas. My 

 friend Dr. Eolleston, F.R.S., has been good enough to compare ThylacinusY/ith 

 the domestic Dog; and he informs me that "the bone is disproportionately- 

 small in the marsupial in question ; but it has precisely the same relation to 

 the external oblique's bifid tendon, to the rectus and pyramidalis (wliich are 

 only imperfectly differentiated from one another and from the inner or upper 

 division of the tendon of the estemal oblique), and, finally, to the peetineus, which 

 it has in the placental mammal." 



2 A comparison of the mandible oi Didelphys with that of Ii^asua is even more 

 instructive. In Ccntetcs the angular jirocess is slightly but characteristically 

 inflected. 



