MERRIAM: THE FAUNA OF RANCIIO LA BREA. 235 



and in the wolves generally, the transverse processes of the atlas are broad 

 transversely, and are formed in such a manner as to give each transverse 

 process an approximately quadrate form. In C. dims the lateral margins 

 of the transverse processes are sometimes so truncated that the form tends 

 toward the quadrate ; but in many cases the margin, beginning with the anterior 

 notch for the vertebral artery, slopes outward and backward, so that each pro- 

 cess tends toward a more nearly triangular form with the apex at the postero- 

 lateral angle. This form of atlas is shown especially well in figure 16. 



Compared with the only specimens of C. occidentalis available for study, the 

 atlas of C. dirus is commonly distinguished ; 1) by the much larger opening of 

 the vertebrarterial canal, which perforates the transverse process almost normal 

 to the blade instead of perforating it obliquely; 2) by the much shallower an- 

 terior notch for the vertebral artery; 3) by the less marked tendency of the 

 transverse processes to project behind the posterior ends of the facets for 

 articulation with the axis. 



The axis (fig. 17) is near that of Canis lupus in form. In lateral view it 

 tends to be short and relatively high compared with most canids. Seen from 

 below it is relatively wide. It is generally characterized by relatively short 

 transverse processes, which often project little if any behind the posterior end 

 of the centrum. A character which seems generally to appear in the axis of 

 this form is the presence of a shallow notch on each side in the postero-lateral 

 margin of the spine between its postero-superior angle and the small tuberosities 

 just above the posterior zygapophyses. This region of the margin is in most 

 canids without a distinct emargination ; there is, however, such a notch in the 

 axis of C. occidentalis. 



The cervicals from number three to number seven do not differ markedly 

 from those of the modern timber wolves. In number three the low spinal 

 ridge is clearly marked in all specimens examined. The postero-superior 

 tubercles above the postzygapophyses vary considerably in size in different 

 individuals. The anterior and posterior limbs of the transverse processes extend 

 slightly beyond the ends of the centrum. On number five the laterally directed 

 posterior tubercles on the transverse processes are well developed. In number 

 six the anterior side of the blade of each transverse process is commonly rather 

 deeply notched immediately anterior to the base of the process arising laterad 

 of the vertebrarterial canal. The inferior side of number seven is marked 

 by a distinct median ridge. 



The dorsals do not differ markedly from those of G. occidentalis. The first 

 dorsal is usually characterized by a relatively great transverse diameter of the 

 postero-inferior region of the spine, and by the tendency to development of 

 a deep longitudinal groove on this region of the spine. Dorsals three to ten 

 are distinguished from those of some of the other wolves by the absence of 

 notches between the anterior zygapophyses and the anterior border of the trans- 



