No. 2.] THE RELATIONS OF PROTOCERAS. 317 



less so than in the male, and extends far forward, nearly to Af, 

 terminating in a short spine, which again is very much less 

 developed than in the male. Above the masseteric ridge the 

 ascending plate of the maxillary is sharply inflected to form a 

 horizontal surface and toward the median line again assumes a 

 vertical direction, thus giving to the bone a step-like section 

 and greatly narrowing the dorsal part of the nasal chamber. 

 The horizontal surface thus formed ends anteriorly in a deep 

 fossa, to which Marsh has already called attention, but in his 

 specimen the fossa appears to be somewhat differently shaped 

 and more distinctly demarcated. In advance oi P 2 the max- 

 illary is very low, its upper border curving gently downward to 

 the premaxillary suture, and its outer surface is flat, there being 

 no large canine alveolus to cause a swelling. This region of 

 the jaw is very long and it bears the chief share in the char- 

 acteristic elongation of the muzzle. In one of the specimens, 

 which may possibly represent a distinct species, the portion of 

 the maxillary which is in advance of p£ is shorter than in the 

 usual type of female skull, and the arching of the upper border 

 which represents the great maxillary protuberance of the male, 

 is thicker and has a more rugose margin. From this process 

 the descent of the border to the premaxillary suture is more 

 abrupt. The lower border of the maxillary fossa, which is a 

 continuation forward of the masseteric ridge, though not rugose 

 like the latter, is more prominent and extends farther upward 

 upon the maxillary process. In these respects this skull 

 approximates the characters of the male more closely than do 

 the long-muzzled females which are more commonly found. 

 The teeth of this specimen are remarkable for the relatively 

 feeble development of the internal cingulum upon the upper 

 premolars and its unusual prominence on the molars. 



The palatine processes of the maxillaries form nearly the 

 whole of the bony palate, the premaxillaries and palatines 

 taking but little share in it. The palate is widest between the 

 first molars of the opposite sides and gradually narrows in each 

 direction from that point, while in front of p£ it is constricted 

 and becomes very narrow ; it is unusually flat both transversely 

 and antero-posteriorly. The faintly marked rugose ridges 



