LVOn] the hares and THEHt ALLIES 4^1 



latter is not narrowed as in the case of Orycfolagiis. The horizontal 

 plates of ihe palate bones are extensively developed and form about 

 half of the bony palate. The portion of the palate bone bordering 

 the maxilla, caudad of the posterior edge of the bony palate, reaches 

 its greatest development in Romcrolagus, Pentalagns, and Prono- 

 lagus, about equally developed in each, where it helps to form the 

 lateral posterior part of the roof of the mouth. The posterior pala- 

 tine foramina are very large in Roiiierolagus; they are in the usual 

 position at the anterior outer angles of the horizontal plates of the 

 palate bones. 



The zygoma of Romcrolagus is very thick and deep. The an- 

 tero-inferior angle is much enlarged and flares outward to a consider- 

 able degree. The foot-like extremity of the zygomatic process of the 

 squamosal is moderately enlarged. The posterior free projecting 

 extremity of the malar is large and long, being proportionally m.ore 

 so than in any of the other genera. 



The audital bullse show nothing peculiar, but the external aviditory 

 meatus is relatively larger than in the rest of the Leporidse, and 

 its outline is oval instead of circular. 



The fenestration of the maxilla is much reduced, about as it is in 

 Pronolagus and Linmolagiis. 



The mandible of Roiiierolagus possesses wide ascending rami, 

 which are nearly vertical instead of sloping backward as in other 

 Leporidae. The angle is well developed and its edge is moderately 

 rounded. The notch between the ascending ramus and the angular 

 process is much larger than in any of the other genera. 



Teeth (pi. xci, 3; fig. 44, 5). — The teeth of Romcrolagus in a 

 general way resemble those of Pronolagus. The first upper incisor 

 has the groove rather deep but not filled with cement. The first upper 

 molariform tooth presents the three usual reentrant angles on the an- 

 terior face, a deep median one and a shallower one on each side. 

 The first lower molariform tooth has a broad shallow reentrant 

 angle on the external surface of its anterior half. The main re- 

 entrant angle extends but half way across the tooth, while a corres- 

 ponding reentrant angle comes in to meet this from the internal 

 surface, both angles contributing to the division of the tooth into 

 anterior and posterior portions. 



The second, third, fourth, and' fifth upper molariform teeth show 

 reentrant angles that extend nearly across the teeth, but not quite so 

 far as they do in Pronolagus. The internal third of the reentrant 

 angles is rather wide; for the external two thirds, the adjacent 

 sides are almost in contact. The posterior portions of the second, 



