CEEODONTA. 301 



the last molar from it. The second true molar is the largest, and the first 

 and third are of about the same size, and not much smaller than the second. 

 The last differs from the first in having the heel narrower in transverse diam- 

 eter. The heels are all basins with the external wall somewhat within the 

 base of the crown. The anterior part of the crown is much elevated above 

 the heel, and consists of the usual three cusps, whose base forms a right- 

 angled triangle, of which the shearing portion forms the hypothenuse. The 

 last premolar is large, rather longer than the first true molar. Its crown 

 consists of a large conic median cusp of wide lenticular section, behind 

 which is a heel with obtuse cutting edge, and an internal basal cingulum. 

 There is a well-marked anterior basal tubercle, and a rudiment of a posterior 

 lobe of the median cusp. No lateral cingula. Of the other premolars it 

 can only be said that the base of the third is as large as that of the fourth. 



Measurements of inferior molars. 



M. 



Length of last four molars on base 0355 



Length of true molars on hase 025 



Length of first true molar on base 0083 



Width of first true molar on base 0050 



Length ef second true molar on base 009 



Width of second true molar on base 0058 



Length of third true molar on base 008 



Length of heel of third 0035 



MIACIS Cope. 



Paleoutological Bulletin, No. .i, p. 2, Aug. 7, 1872. Proceed. Amer. Philos. Soe., 1872, 470. Uiniacyon Leidy, 

 nomen nudum, Proc. Acad. Nat. Sci. Phila., 1872, p. 277 (December, not published until 1873). 

 Report U. S. Geol. Surv. Terrs., i,p. 118, nomen nudum. 



This genus was proposed for a species which was represented at the 

 time by a portion of a mandibular ramus, which had supported the last 

 three molars. The portions of the latter preserved were stated to resemble 

 corresponding parts of Canidce, with approximations to those of Stypoloplms. 

 Subsequently Dr. Leidy described the mandibular ramus, containing most 

 of the teeth, of a larger species; and a fragment of the lower jaw of a still 

 larger species. From the former of these specimens I derive the greater 

 part of the following diagnosis. I premise with the statement that there are 

 in this specimen five premolar teeth, the third of which is apparently three- 

 rooted, and stands partially transversely to the axis of the jaw. I suspect 



