804 “The Condylarthra. x [August, 
There are four species of the genus Haploconus. Theyal 
differ from the species of Anisonchus in the entire simplicity o 
all the superior premolars, excepting the fourth. The inter 
nal cusp of the latter tooth presents the same variations as tha — 
of the species of Anisonchus. In the type, H. lineatus, the - 
cusp is an elevated cingulum, and in AH. entoconus (Fig 
II a ò) it is conical, The latter is the largest species of the i 
genus ; the former comes next in size, and is the most 
In both, the premolars are larger than the true molars, a character 
especially conspicuous in the Æ. dineatus (Fig. 13a). This spe — 
cies is abundant, though the Æ. enzoconus is not rare in the lower 
Puerco beds. In some of the species of this genus the posterior — 
internal accessory cusp is so produced as to become the apex of 
the triangular superior molar. In the Æ. xiphodon Cope, the 
inferior premolars are elongate and much compressed, so as to be 
quite sectorial in function (Fig. 13 c). 
Fic. 13.—Species of Haploconus, natural size, from the Puere ea iad: wie a 
z m A 
Mexico. Fig. a, Haploconus lineatus, anterior part of craniu eaey ini ; 
from below. Fig. 4, left mandibular ramus of same species, d of right ramis 
inner side ; 6’, do, from above. Fig. c, Haploconus xiphodon, et Ters, F v. 
mandibuli, from above. Original, vit Report U. S. Geol. Survey . 
Hayden in charge, Vol. 111. - 
a inferior molat: ; 
In the genus Zetodon we have a distinct form of i nts in pai 
Each crown is theoretically composed of four cresce! coh 
in each of which the concave faces are present 
other, an arrangement unknown in any other gen 
us of 
