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



is slender, light and complex in structure as compared with the massive 

 and rounded D. cornutus. The molar teeth are no longer in the crown 

 than those of Metarhinus earlei. The jugal process of the maxillaries 

 arises at a point back of the last molar rather than beside it as in D. 

 longiceps. There is no offset in the palate between the last molars, 

 though the primary position of the posterior narial opening is marked 

 by a slight rugosity. 



D. fluminalis is most nearly related to D. intermedins. The skull 

 exceeds in length the type of that species in the ratio of 520 : 465 mm. 

 The molar teeth are proportionately much smaller; the series measures 

 relatively 99 : 109 mm. The position of the posterior narial opening 

 is the most distinctive character, appearing much farther back in 

 D. fluminalis than in any other described species. The two forms 

 agree more closely in the tapering form of the nasals and in the narrow 

 recess separating them from the maxillaries. 



MEASUREMENTS OF 

 DOLICHORHINUS. 

 IN MILLIMETERS 



Skull, length incisors to condyles 



breadth across arches 



" above orbits 



post-orbital process to condyles 



last molar to condyles 



length of free nasals 



greatest breadth of nasals 



post-glenoids to condyles 



(median line) 



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 .... 



Mandible, length condyles to incisors . . 



height, condyles above angle 



" length of molar-premolar 



series 



' ' length of molar series 



" crown of canine 



" diameter crown of canine. . . 

 " depth of ramus from base 



of P 3 



" depth of ramus from base 

 of M 3 





•So 



545 : 

 260 



310* 



152 

 81 



224 

 140 



15 

 40 



S 



Q N 



595 



285 



300 



140 

 214 



135 

 40 

 22 

 16 



D. longiceps 

 Field Museum 



550 

 247 



134= 

 305 

 263 

 170 

 79 



122 

 212 

 131 



24 

 17 

 14 

 52 



560 : 



255 

 130 



305 

 280 

 i6o J 



121 

 200 

 124 



40 

 67 



53o 

 240 : 



295 



258 



115 

 192 

 121 



16 

 23 

 45 



535* 



132 

 264 

 259 



114 

 198 

 122 



54 



400 

 159 



209 



123 



29 



16 



70 



57 



"is 



a « 



520 



233 

 Il6 



137 



57 



171 



105 



32 



18 



44 



* Estimated. 



