EDENTATA OF THE SANTA CRUZ BEDS. 215 







closely with the type, and, somewhat doubtfully, another skull in the 

 American Museum of Natural History (No. 9176), which differs in 

 many respects and may perhaps be referable to another species ; some of 

 these differences are, however, evidently due to the immaturity of this 

 individual. 



In the type and in the Princeton specimen, i is very thin and much 

 compressed laterally, quite elongate antero-posteriorly, while in the third 

 specimen this tooth is of the usual oval form and is much less compressed 

 and the diastema between - 1 and ^ is considerably shorter. This tooth is 

 inserted near the anterior end of the maxillary, even the facial plate of 

 which extends but little in advance of it. The molariform teeth are, in 

 the typical examples, relatively small, of transversely oval shape and 

 antero-posteriorly compressed, while in No. 9176 these teeth are of a 

 more rectangular shape (Plate XXXVI, fig. 4) ; Ms the largest of the 



series and - is very small. 



MEASUREMENTS. 



No. 9,176. No.. 1 5, 596. 



Upper dentition, length 049 .054 



" A-fi. 031 .030 



J-, length (i. t., antero-posterior diameter) 006 .008 



" width (i. e., transverse diameter) .005 .0045 



, length 007 .006 



" width 008 .009 



, length 007 .0065 



" width 009 .010 



, length 006 .006 



" width 0085 .0095 



i, length 004 .005 



" width 007 .008 



The skull is of the type of H. robustns, though on a distinctly smaller 

 scale; it is short and depressed, but very broad; the parietal eminence 

 rises very little above the occipital crest and the cranium is low and 

 broad, contracting forward very gradually to the shallow postorbital con- 

 striction, whence the skull again expands forward in the same gradual 

 manner to the very broad forehead and muzzle ; the rostrum is con- 

 stricted by the deep preorbital fossse. The sagittal crest, at least in the 

 adult, is better developed than in most species of Hafialofis, but is never 

 conspicuous, and in the young specimen referred to this species there is 

 no crest, merely a broad, indistinct sagittal area. The occiput is nearly 



