Measurements. M. 



"Width of crown of last molar , 0015 



Length from M. 1 to infraorbital foramen 007 



Depth of mandibular ramus at M. 2 006 



"Width of face of inferior incisor 0016 



Entoptychus pianifrons, sp. nov. 



A larger species than the E. cavifrons, represented in my collection by 

 parts of crania, and rami. The former show that besides the superior size, 

 this species differs from the E. cavifrons in the absence of the superciliary 

 ridges, and hence perfect flatness of the interorbital region. The latter is 

 also wider, measuring five-sixths the width of the muzzle at its middle, 

 while in the E. cavifrons it is only half as wide. The subjoined measure- 

 ments give the characters in detail. 



Measurements. M. 



Width of interorbital space 007 



" muzzle at middle 0086 



Elevation of skull from second molar .0130 



Length of inferior molar series 0072 



Depth of ramus at M. 2 0072 



Width of inferior face at M. 2 0043 



" " incisor 0018 



Distance between infraorbital foramen and M. 1 0050 



Entoptychus crassiramis, sp. nov. 



This, the largest species of the genus, appears to have been less abundant 

 than the two already described. I refer to it portions of two crania and 

 three mandibular rami, found separately. The superior size of the parts is 

 obvious, the posterior three superior molars having the same longitudinal 

 extent as the entire series of the E. cavifrons. The gradation in the size 

 of these teeth, is as in that species, the grinding surfaces diminishing 

 rapidly in extent posteriorly. The superciliary ridges are not well pre- 

 served, but were probably thickened as in E. cavifrons, and the iuteror- 

 bital space was relatively as narrow, and not so wide as in E.planifrons. 

 The measurements below exhibit the characters more exactly. 



Measurements. M. 



Width of skull between orbits 007 



Elevation of skull from second molar 015 ' 



Length of series of superior molars. 0115 



t.. . c t , ( anteroposterior 003 



Diameter of second molar-? ' 



' transverse 004 



Diameter of fourth molar { anteroposterior 002 



I transverse 002 



In the mandibular rami the inferior masseteric ridge extends to below 

 the anterior border of the first molar, and is very prominent and acute. 

 It results that both the exterior and inferior aspects of the ramus are con- 



