162 B. 8. Lull — Fauna of the Dallas Sand Pits. 



Measurements. 



S. fatalis 



holotype 



after Leidy 



mm. 



Carnassial 



Depth, infraorbital foramen to 



base of crown 31.75 



Breadth ant. -post, diameter of 



crown 33,337 



Thickness at position of inner but- 

 tress 15.875 



Depth of principal cusp 19.05 



Averao^e ratio . 



Eatio S 



. calif ornicus 





No. 10204, 





Y. P. M. 





mm. 



0.793 



40 



0.803 



41.5 



0.992 



16 



0.846 



22.5 



0.858 



S. fatalis 



No. 1.52 



S.M.U. 



mm. 



Length of parietal crest 110 0.866 127 



Breadth of brain-case 93 1.022 91 



Breadth of occiput at upper edge 



of foramen magnum 80 0.920 87 



Height of occiput 65 0.890 73 



Breadth across mastoids 123 0.898 137 



Breadth across occipital condyles . 60 0.87 69 



Breadth at summit of occiput .50 80 • 



Average ratio 0.876 



The Dallas specimen differs from S. calif ornicus not 

 only in its lesser size, but in its relatively narrower 

 occiput, the proportions of which compare more nearly 

 with those of the tiger. The brain-case, on the other 

 hand, is relatively larger in the Texas specimen, and the 

 sagittal crest thinner ; another distinction lies in a sharp 

 thin vertical keel on the basi-occipital in 8. calif ornicus. 

 Some of these details, as in the more powerful occiput 

 and greater size of the latter, may indeed have been 

 sexual, but the assumption is that the species are distinct. 

 I have, however, no assurance that the Dallas specimen 

 is distinct from 8. fatalis, with the proportions of which 

 it approximately agrees. The discovery of a carnassial 

 attached to the cranium in the Dallas sand pits alone can 

 give assurance of identity or disagreem.ent. Until then, 



