NOTES ON THE CANID/E OF THE WHITE KIVER OLIGOCENE. 6b\) 



slightly concave transversely, but has a low median convexity, with very feebly devel- 

 oped keel, the convexity being much less prominent than in Daphcenus. 



The exoccipitals are low and wide and so convex in the median line that this por- 

 tion projects much behind the sides. The condyles are low and depressed and are 

 separated on the ventral side by a narrower, deeper and more V-shaped notch than 

 in the modern wolves or foxes. The paroccipital processes are very small and project 

 almost directly backward, as if to avoid the auditory bulla, with which they are not 

 in contact at any jDoint. 



The supraoceipital is a large bone, both high and broad ; dorsally it is reflected 

 over upon the cranial roof, and in this region is thickened and diploetic. 



The mastoid is exposed quite extensively upon the occipital surface, somewhat more 

 so than in the modern representatives of the family, and as the distance between the 

 paroccipital process and the postty mpanic process of the squamosal is greater than in the 

 latter, the mastoid occupies a rather more lateral position. The mastoid process is very 

 small, almost obsolete. 



The sphenoid bones cannot be described, as none of the specimens allow the limits 

 of these elements to be determined. 



The tympanic differs in very important ways from that of Daphcenus. In the first 

 place it is inflated into a very much larger auditory bulla, filling out the entire fossa 

 and leaving no part of the periotic exposed ; and in the second place, the posterior cham- 

 ber of the bulla is ossified and fused with the anterior chamber. The line of junction 

 between the two elements- which compose the bulla is very plainly marked by a groove 

 upon the external surface, and shows the posterior chamber to be considerably the smaller 

 of the two. I have not been able to detect any, even partial, septum between the two 

 chambers, but such a septum as that of Canis may well have been present. The bulla 

 is relatively as elongate as that of Canis, but is much narrower and more compressed, 

 and therefore has a less inflated ap])earance. The external auditory meatus is a very large, 

 oval aperture, without any tubular prolongation, the borders being flat, except the ante- 

 rior one, which forms a more prominent lip than in Canis and partially conceals the 

 postglenoid foramen. The auditory bulla of Cynodietis is thus thoroughly cynoid in 

 development and displays no resemblance to the characteristic viverrine type. 



The parietals are proportionately very large bones and make up the greater part of 

 the sides and roof of the cranium. Throughout their lene'tli they unite to form a very 

 low and weak sagittal crest, which becomes moderately prominent only at the concavity 

 of the cranium formed between the occipital crest and the hinder Avail of the cerebral 

 fossa. Owing to the larger size and backward extension of the cerebral hemispheres, as 

 well as to the lowness of the occipital crest, this concavity is shorter and much shalloAver 



