20 A Remarkable Ground Sloth 



of forty feet in a well in Wheeler County, Texas. It belonged to an older individual 

 than ours, more robust, with many of the sutures obliterated. In the texanum skull the 

 limits of the temporal muscle area are clearly denned and the region itself is slightly 

 rugose. There is no trace of this in the Yale skull. There is more modeling of the 

 frontal area above in the former, and the lachrymal is more pronounced. The frontal 

 foramen is farther forward, and the muzzle flares, as it does in certain Rancho la Brea 

 skulls. The Texan skull is much broader than ours over the squamosals, whereas the 

 frontals are more highly domed in the latter. The tooth row in the Texas skull is 

 somewhat shorter, measuring 56 mm. to 58 mm. for the Yale specimen, as the last 

 molar is slightly smaller. 



Hay's specific distinctions from shastense are: Pterygoid bulla widely open be- 

 low; anterior tooth with hinder margin transversely concave; hindmost upper tooth 

 nearly as large as the others with a deep furrow on the hinder face. As the teeth are 

 rootless and continually growing, they would probably change their proportions 

 somewhat during life, and the other dental distinctions stressed by Hay seem hardly 



of specific value. 



With regard to the pterygoid bullae, these are clearly imperfect, which makes the 

 present opening much larger than it was originally. Where the actual margin of the 

 aperture is preserved, as it is at the posterior end, it corresponds exactly with that of 

 the Yale skull, and it is reasonable to suppose that, were the margin entire, the agree- 

 ment would be complete. Hay himself expresses doubt as to this detail. Certainly the 

 geographic localities are within the range of one species and possibly of one indi- 

 vidual, if they were at all given to wandering. Stratigraphically no comparison can 

 be made. My conclusion is that the texanum type is therefore conspecific with the Yale 

 specimen and, like the latter, should be referred to N othr other ium shastense. 



