30 Field Museum of Natural History — Geology, Vol. IV. 



but in reduced size. In the broader headed M . cristatus there is a 

 trace of this element but in the later skulls of M. earlei it is wanting 

 entirely. In the lower dental series there is a corresponding strengthen- 

 ing of M 2 and M 3 , a reduction, sometimes a loss, of P 1 and a slight 

 elongation of the post-canine diastema. The Uintah representatives 

 of this species are somewhat broader headed and more massive than the 

 Bridger type. 



MEASUREMENTS OF 



SKULLS OF METARHINUS 



IN MILLIMETERS 



Skull, length incisors to condyles 



breadth across arches 



" between orbits 



post-orbital process to condyles 



last molar to condyles 



length of free nasals 



greatest breadth of nasals 



post-glenoids to condyles 



(median line) 



breadth across condyles 



greatest depth of arch 



length of molar-premolar series. . 



" " molar series 



" crown of canine 



diameter crown of canine 



length of diastema 



narrowest point in sagittal area 

 breadth of orbito-nasal area .... 



>>2 



• - 3 

 I 3 



§ d 



352 

 205 

 112 

 214 



107' 



145 



86 



9 

 39 



0,0 



"C2 



406 



2I0f 



"4t 



205 



189 



128* 

 68 



87 



79 



55 



160 



93 

 24 

 18 

 11 

 10 

 4i 



a N 



406 

 220' 

 107 

 212 

 193 

 115 



68 



82 

 51 

 155 

 93 

 29 

 20 

 10 



39 



15=2 

 £ 



3»5 : 

 240 



145 

 215 

 195 



90 



92 



4 

 43 



5 3 



390 

 237 

 I37 ! 

 198 



182 



75 



169 

 104 



11 



6 

 50 



S3 



388 

 245 



142 



184 

 120 



74 



73 



79 



50 



158 



100 



29 



15 



8 



9 



42 



O to 



405* 



255* 



220* 

 220* 



130* 



80 " 



170 

 IO3 



30 

 16 

 II 

 17 

 50 



*Estimated. fDistorted. 



