168 Marsh — Principal Characters of the Protoceratidce. 



long flexible nose, if not a true proboscis. The only existing 

 ruminant thus equipped, known to the writer, is the rare 

 Saiga antelope (Saiga Tartarica, Gray) from the steppes of 

 Siberia. A comparison of a Protoceras skull with that of the 

 Saiga antelope plainly indicates, in the nasal region, an iden- 

 tity of function doubtless accompanied by a similar nasal 

 appendage, and it is of interest to find such evidence of this 

 feature in a representative from the Miocene of North America. 



The general form of the male skull of Protoceras is long and 

 narrow, with the facial portion much produced. The prom- 

 inent horn-cores, however, serve to obscure its real shape, 

 which is more apparent in the female skull. Seen from the 

 side, as in Plate III, it appears unusually low, with the orbit 

 well behind. Its greatest width is in the posterior region, as 

 shown in Plates Y and YI. 



The premaxillaries are small and edentulous. Their anterior 

 extremities are depressed, and more or less expanded trans- 

 versely, as in typical ruminants. The outer suture between 

 the prem axillary and maxillary is short, and persistent even in 

 adults, as indicated in Plates II and III. Seen from below, 

 the premaxillaries form together the palatal surface in front of 

 the maxillaries, each sending backward a narrow process which 

 is inserted between the divergent maxillary plates. The 

 anterior palatine, or incisive, foramina are situated on the sutures 

 separating the two bones, as represented in Plate Y. 



The maxillary bones are greatly developed, being much the 

 largest elements of the skull, as is well shown in Plate II. The 

 anterior extremity supports the large descending canine tusk, 

 and is hollowed out to contain its base. The high anterior 

 horn-cores are formed entirely of the maxillary bones, which 

 are greatly strengthened to support them. These horn-cores 

 are more or less recurved, and in the type species, their sum- 

 mits are triangular in outline, as seen in Plates II and. Ill, and 

 in the cut below, figure 4. In a new species, Protoceras 

 nasutus, the summits of the maxillary horn-cores are oval in 

 section, as shown in cut 5. Another characteristic feature of 

 the genus Protoceras, which is seen in both sexes, is a strong 

 lateral ridge extending nearly horizontally across the outer 

 face of the maxillary bone, and continuing backward to the 

 orbit. It is also present in the other members of this family. 

 In the male skull here described, this ridge begins near the 

 base of the maxillary horn-core, and, expanding into a prom- 

 inent tubercle, just above the antorbital foramen, continues 

 backward by an upward curve, and passes into the ridge of the 

 malar bone extending beneath the orbit. In both sexes, the 

 anterior portion of this lateral ridge, with its characteristic 

 tubercle, forms the lower border of a deep, well-marked 



