THE OSTEOLOGY OF VULPES MACROTIS. 397 



Canidce? who first established or distinguished these two series of the Canidse, 

 and in doing so he admitted that " within each of these series there are consider- 

 able modifications, which give rise to corresponding terms in the two series." It 

 appears that the first of these modifications is in the proportion of the sectorial 

 and next following teeth relatively to the basicranial axis, which axis is taken at 

 the value of 100, and is a line, measured mesiad on the base of the skull (bisected) 

 extending from the posterior border of the basioccipital bone to the articulation 

 between the presphenoid and the ethmoid. It is evident, as Professor Huxley adds, 

 that the "measurements of the other parts of the skull can then be expressed in 

 terms of 100, and their development, irrespectively of the absolute size of the 

 animal, becomes apparent." 



The second modification noticed refers to the extent of the areas for the 

 insertion of the temporal muscle upon either side of the skull. Huxley observed 

 that " in all young canine animals, the upper edges of the attachment 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 approximation of the temporal muscles. This approximation 

 takes place 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 supra-orbital 

 processes and inclose the glabellar area." This very distinctive feature is well 

 seen in the skulls I have at hand, for in Vulpes velox and V. macrotis, the sagittal 

 area, though unlike in form in both, is large and distinctly defined, while in all 

 the skulls of a series of Cams latrans, collected by me in New Mexico and Arizona, 

 this area is reduced to a median ridge of narrow width, and extending as far for- 

 ward as the coronal or fronto-parietal suture. This ridge is longitudinally marked 

 in the median line by the sagittal suture for the anterior two-thirds of its length. 



In speaking of a third modification, Huxley remarked that " In most of the 

 Alopecoids, the contour of the inferior margin of the angular process continues the 

 direction of that of the inferior margin of the ramus in front of it ; and this slopes 

 gradually upward and backward. In C. littoralis and C. cinero-argentatus, 

 however, the inferior contour of the ramus in the region of the attachment of the 

 digastric muscle, in front of the angular process, is inclined almost at right angles 

 to the latter, and forms a sort of rounded ' subangular lobe ' beneath the angular 

 process. De Blainville long since figured and called attention to this feature of the 

 mandible in C. cinero-argentatus T The angular processes, as well as the sub- 

 angular lobes, are characteristically the same in Vulpes velox, V. -macrotis and in 

 C. latrans. They quite closely agree with what Professor Huxley found in C. 

 fulvipes. Further on in the present paper reference will again be made to some 

 of the data set forth in this excellent memoir. 

 3 P. Z. S., 1880, p. 248. 



