408 



MEMOIRS OF THE CARNEGIE MUSEUM. 



Contour of Skull compared with the Dentition — Continued. 



Contour of Skull. 



G. No. 2408. Paratype of 

 D. cooki. Rather young 

 female. 



H. No. 2463. Old female 

 with pathfilogical de- 

 formity. 



No. 2816, Male. 

 No. 2478, Male? 



Skull somewhat depres.sed by 

 cru.shiug, especially over the poster- 

 ior part of the nasals and the fron- 

 tals. 



Nasals not projected in front of 

 the premaxillaries, ixiinted, no horn- 

 cores indicated, but nasals thickened 

 in this region ; little or no const riction 

 back of the thickened region; fron- 

 tals broad and flat; temporal ridges 

 fairly prominent and early united to 

 form a sagittal crest before the inion 

 is reached (the latter is broken off) ; 

 brain-case broad; zygomatic arches 

 slender. Skull projiortionally broad 

 and low, due partly to crushing. 



Dentition. 



Skull crushed so as to produce an 

 unusually, high occiput. Frontal 

 and nasal regions ciuite symmetrical. 

 Anterior portion of nasals and pre- 

 maxilhr broken off. 



Anterior portion of skull not un- 

 like that of No. 1572 (type of D. 

 cooki) in fact the general contour is 

 similar. However, the sagittal re- 

 gion is narrower, there being a de- 

 cided sagittal crest in the present 

 specimen. 



Zygoma lighter, without the ru- 

 gose area on the posterior angle. 

 The comparatively light structure 

 of the skull clearly indicates a fe- 

 male specimen. 



The greater portion of skull No. 

 2816 is preserved, while No. 2478 is 

 only represented by a portion of the 

 top and back. 



These two specimens are no less 

 unique than No. 2463 just de- 

 scribed. 



The chief feature is the inflated 

 condition of thefrontals, which is not 

 unlike that in Rhinoceros hicornis, 

 except that in the fossil specimens 

 the swollen area is confined more to 

 the posterior portion of the frontals. 

 In No. 2478 the inflated area is 

 more pronounced than in 2S16 and 

 also differs in the median line from 

 the latter, 'having this inflated region 

 continued backward as a promi- 

 nent rounded ridge between the tem- 

 poral ridges. 



Judging from the heavy and ru- 

 gose zj'gomatic arches on No. 2816 

 the skull is undoubtedly that of a 

 male. 



Dentition comparatively little 

 worn. P' well worn. P^ with medi- 

 fos.sette isolated, especially on tooth 

 of right side, tiny crenulation on the 

 face of the crochet wall, post-fossette 

 widely open behind. P-* with medi- 

 fossette isolated, crenulation on 

 crochet as on preceding tooth, post- 

 fossette large. P'' with medifossette 

 isolated, especially on tooth of left 

 side, post-fossette large; prominent 

 cingulum on internal faces of pre- 

 molars. M' with moderate rounded 

 crista and heavy crochet, but not 

 united to form a closed medifossette, 

 post-fossette broadly open poster- 

 iorly. M^ with more prominent 

 crista, which very nearly unites with 

 the crochet, post-fossette large. M^ 

 well erupted, but not yet in contact 

 with the lower teeth, crista and 

 crochet rather delicately developed. 

 Cingulum little developed on the 

 internal faces of the molars. 



P^ of left side represented only by 

 an extremely thin band of dentine. 

 P^ and M' closely succeeding one 

 another, nearly closing up the space 

 for P''. This was accomplished dur- 

 ing the life of the animal. M' of 

 both sides have curious metastyles 

 located on the postero-internal angle, 

 a deep fissure separating them from 

 the main body of the teeth; median 

 valley open, but crista and crochet 

 well shown. Dentition nuich worn 

 (See Fig. 4.) 



The dentition of No. 2816 is essen- 

 tially that of D. cooki, while in No. 

 2478 there are no teeth represented. 



