810 THE WHItE EIVER FAUNA. 



DOMNINA Cope 



Paleontological Bulletin No. 16, p. 1, August, 1873. Ann. Report U. S. Geol. Surv. Terrs., 1873 (1874), 

 p. 469. ? Miothen Cope, Synopsis New Vert. Colorado, 1873, p. 5. 



The evidence of the distinctness of this genus from Peratherium was 

 originally seen in the position of the mental foramen, which is situated 

 under the third inferior molar (counting from behind), instead of under the 

 fourth. The deduction from this feature is that there is at least one molar 

 tooth less in either the true or premolar series. Although a verification of 

 this view has not yet been obtained from specimens which display the whole 

 series, I confidently anticipate it. The true molars differ in their form from 

 those of the species of Peratherium. Thus the posterior external cusp is 

 a true crescent of the same form as the anterior one, but rather smaller. 

 Both internal cusps are at the summits of strong subvertical ridges. The 

 molars rapidly increase in size forwards, the third being little more than 

 half as large as the first. 



I associate with the typical species, D. gradata, a second one, which is 

 represented by two mandibular rami in which the molar teeth are worn by 

 use. They show that the posterior inner cusp had a crescentic base as in 

 D. gradata, and that the last molar is even more reduced, being only half as 

 large as the penultimate. The rami are both broken off posterior to the posi- 

 tion of the mental foramen, so that its position cannot now be ascertained. 



DoMNINA GRADATA CopC. 



Paleontological Bulletin No. 16, p. 1, August, 1673. Annual Report U. S. Geol. Surv. Terrs., 1873 (1874), 



p. 469. 

 Plate LXII ; figs. 25-6. 



Represented by the parts of the mandibular rami of two individuals 

 which support the three last molars. These show that the anterior base of 

 the coronoid process is wide and oblique, and that both its external and in- 

 ternal boi'ders are prominent. The line of the inner alveolar border is con- 

 tinued as a ridge, which projects beyond the inner face of the ramus below it. 



The inner cusps of the molars are much smaller than the external cusps, 

 and the median is larger than the anterior or posterior. The anterior is 

 little prominent, is well in advance of the median, and is separated to the 

 base on the inner side. There is no fourth cusp or heel of the inner side of 



