258 Annals of the Carnegie Museum. 



The depth of the mandible is greater than that of the type of Aphe- 

 lops ceratorhinus, it is much thinner transversely, and the angle is not 

 so large. 



The femur is long and very slender for so large a rhinoceros. Only 

 portions of other bones are preserved. 



Measurements. 



mm. 



Length of skull from tips of nasals to crests of occiput 567 



Width of skull including zygomatic arches, greatest 330 



Width of skull at post-tympanics 200 



Height of skull at orbit 205 



Height of skull at occiput 200 



Length of nasals, approximately 170 



Height of paroccipital processes 51 



Width of paroccipital processes at base 51 



Height of mandible under P 4 85 



Height of ascending ramus of mandible, estimated 255 



Width of ascending ramus of mandible from M 3 backward 150 



Length of upper molar-premolar series 265 



Length of lower molar-premolar series 268 



Length of femur about 520 



Proportion of height of skull at occiput to length of top of skull 



= 35- 2 : 1QO - 



The Flint Creek beds, from which this rhinoceros was obtained, are 

 closely related in time to the Deep River beds of the Smith River 

 Valley in Montana, though Palceojneryx ? borealis is the only species 

 that is now known to be common to the two formations. 



Comparisons of Aphelops montanus with other species of 

 Rhinoceroses. 



Comparison with A. ceratorhinus. 

 Aphelops montanus much resembles A. ce7'atorhinus in the size and 

 proportions of the skull, in having a complete upper premolar series, 

 and in having teeth which are not strongly hypsodont. Some of the 

 differences are : the lack of horn -rugosities on the nasals of Aphelops 

 montanus, the absence of an inward-turning scroll-like border on the 

 posterior outer portions of the nasals, the different form of the poste- 

 rior basal elements of the skull, and of the postero-superior portion. 

 There are some differences in the proportions of the teeth, especially 

 the molars, as is shown in the following measurements which are 

 arranged for comparison : 



