lvon] the hares and their allies 417 



of the horizontal plates of the palate bones, as in the case of the 

 other genera of Leporid?e. 



The zygoma is rather thin and shallow ; its antero-inferior angle is 

 moderately enlarged. The foot-like extremity of the zygomatic proc- 

 ess of the squamosal is rather short, about as it is in the genus Lcpus. 

 The posterior free extremity of the malar is short. The root of the 

 zygomatic process takes its origin close to the squamoso-frontal 

 suture, closer than in any other genus, although Romcrolagns and 

 Lhnnolagns show an approach to this condition. 



The audital bullae in Pronolagiis are remarkably small. 



The fenestration of the maxillae is developed to a small extent only, 

 about as in Romcrolagns and Limnolagiis. 



The mandible in general is quite like that of Lcpus, but the lower 

 edge of the angular process is decidedly straight. 



Teeth (pi. xci, 8; fig. 44, 23). — First upper incisor has the groove 

 simple, very shallow, and unfilled with cement. The first upper mo- 

 lariform tooth has the three usual reentrant angles on the anterior 

 surface very deep, deeper than they are in the other genera, except 

 Pcnfalagiis. The first lower molariform tooth, like the same tooth 

 in Roiiici'olagiis, departs from the typical form. The tooth is di- 

 vided into anterior and posterior portions not by a single reentrant 

 angle extending inward from the external face, but by two reentrant 

 angles, one from the internal, one from the external face, which 

 meet near the center of the tooth. The external angle is the broader 

 and shallower of the two. The internal is deeper and the adjacent 

 sides of the angle are nearly in contact. The anterior limbs of both 

 the reentrant angles are plain and heavy, the posterior limbs rela- 

 tively narrower and decidedly convoluted. On the anterior face of 

 the first lower molariform tooth are two deep, simple, reentrant 

 angles. On the external face of the anterior portion of the tooth 

 is a broad, shallow, reentrant angle. In the second, third, fourth, and 

 fifth upper molariform teeth the reentrant angles extend nearly the 

 whole distance across the teeth. The internal half of the angle is 

 rather wide and open, differing in this respect from the other genera 

 except Ronierolagus. The enamel of the reentrant angles is cre- 

 nated. The second, third, and fourth lower molariform teeth are 

 divided by the usual deep reentrant angle, into anterior and posterior 

 portions, the lateral diameters of which are equal to one another. 

 The last upper molar is relatively larger in Pronolagns than in the 

 other genera and its grinding surface is somewhat lozenge-shaped. 

 The last lower molar has the reentrant angle which divides the tooth 

 into a larger elliptical anterior portion and a smaller circular pos- 



