I9I5-] LOWER PLIOCENE SNAKE CREEK BEDS. 87 



either of the better known Miocene species {P. laticeps and P. al- 

 tiramis) from which it can be separated by differences both in size 

 and proportions. 



Measurements. 



Length of jaw 208 



Depth beneath pj 57 



Depth beneath m^ 53 



Depth beneath back part of m^ 55 



Depth beneath last lobe of mj 94 



Depth coronoid to angle 147 



Length lower dental series 132 -)- 



Length lower premolar-molar series 125 



Length lower premolar series 50 



Length lower molar series 75 



Protolabis princetonianus sp. nov. 



Type No. 12053 Princeton University Geological Museum, col- 

 lecting locality lOOoC, an uncrushed skull, sand-worn on the right 

 side which lay uppermost, associated with most of the left ramus 

 of the lower jaw, a fragment of the right ramus and an ulna-radius. 

 The limb bone belongs to a camel but may not pertain to the same 

 individual as the skull. In size, there is close agreement with Proto- 

 labis longiceps Matthew from the Colorado Loup Fork (Pawnee 

 Creek beds), but a comparison of the two skulls brings out certain 

 minor differences which appear to be of specific value. In P. prince- 

 tonianus, the anterior facial vacuity is far larger than in the Col- 

 orado form, with the premaxillje extending above it and reaching 

 farther back than in that species. Another marked diiterence ap- 

 pears in the absence of an abrupt constriction of the face in front of 

 p-^ which produces the sudden incurving of the tooth row seen in 

 longiceps in contrast with the gradual taper of this region in the 

 Princeton specimen. Various differences in dental structures are 

 also noticeable, as follows : p- thicker and heavier and p^ less re- 

 duced and with posteroexternal groove deeper than in P. longiceps; 

 p-, if anything, larger in longiceps than in princetonianus. Lower 

 premolars somewhat less reduced and molar crowns somewhat 

 higher, and posteroexternal groove in p^ placed nearer hinder end 

 of tooth than in longiceps; pg- with distinct anterior cusp which is 

 absent in the last named form. 



