COPE.] PALEONTOLOGY MIOCENE PERIOD. 469 



Measiirements. 



M. 



Length of last three molars 0.0052 



Length of third true molar 0024 



Elevation of third true molar .0018 



Depth of ramus at third true molar 0023 



Two specimens. 



DOMNmA, Cope. 



Paleontological Bulletin, No. 16, (August 20, 1873,) p. 1.— Synopsis Vertehrata Colorado 

 p. 4, (?) ; Miothen, Cope, loc. cit, pp. 4-8. 



Three true molars, the last reduced in size ; first molar large, with the 

 foramen mentale posterius below it, and a small alveolus for the root of 

 a premolar in front of it. In front of this a considerable alveolus-like 

 cavity rises toward the border, but is interrupted by fracture. These 

 characters are derived from the specimen of Z>. gradata. In D. crassige- 

 nis, the last molar is still more reduced. In none of the species is the 

 premolar series preserved. 



Portions of two crania already mentioned are described here pro- 

 visionally and without final reference. The form is narrower across 

 the frontal region than in Serpetotherium fugax and plane above. The 

 muzzle is abruptly contracted at the base, and maintains a narrow, 

 compressed form to the end ) the nasal bones are convex in section, 

 and narrow to their posterior extremity. There are three prem axil- 

 lary teeth on each side, the anterior of which is enlarged and directed 

 downward and a little forward ; base of crown an antero-posterior oval ; 

 of last, round. The numbers of molars and premolars is probably 

 3-3 5 but the alveoli of the last true molars are obscured, so as to 

 leave some slight question as to the presence or absence of a fourth. 

 The first " premolar " is in the position of the canine of Serpetotlierium^ 

 and probably represents that tooth, as there is no caniniform tooth in 

 the present species. It is two-rooted, compressed, and with triangular 

 profile. It is both preceded and followed by a short diastema. The 

 other premolars are two-rooted. 



Measurements. 



M. 



Length of premolar series of No. 1 0.0054 



Length to M. 1 of No. 1 0090 



WidthatP. m. 2ofNo. 1 0027 



DOMNINA GKADATA, Cope, loc. cit, p. 1. ^ 



Crowns of the molars composed of two rows of alternating tubercles, 

 with an odd one in front. The inner tubercles are much the more ele- 

 vated, and form the apices of Vs, of which the inner commence the 

 limbs. 



Three rows of acute tubercles on the inner, two on tjie outer side of 

 each dental crown, the last pair of the last crown fused into a heel ; the 

 middle outer and anterior inner forming together a notched, sectorial 

 yoke. A low cingulum on outer, none on inner basis of tooth-crown ; 

 enamel smooth. 



Measurements. 



M. 



Length of basis of three molars 0.0055 



Length of basis of first molar 0023 



Length of basis of last molar 0015 



Depth of ramus at first molar — 0026 



Width of first molar 0015 



