OF THE MESOZOIC MAMMALIA. 
219 
liofessor Marsh in view of the supposed close relationship of this genus to 
Plagiaulax places but two of the upper teeth in the molar series, giving the post-incisor 
ormula as pm ^ ml This can hardly be correct since the three premolars are very 
sharply separated from the molars by many details of structure such as the number of 
tubercles, the internal cingulum etc.. The first and second molars of AUodon have 
their crowns somewhat flattened on the inner sides but not worn as in Bolodon. This 
further increases the uncertainty as to the character of the lower dentition in this 
family. 
CHIEOX, Cope L 1888 . 
Dentition, il cl pm! m!. The number of premolars is somewhat uncertain. 
This genus may be provisionally placed in the same family, sabject possibly to re- 
moval later when its dentition is more fully known. It is represented by a maxilla 
with three premolars and two premolars in situ. The most anterior premolar is the 
largest, the series decreasing posteriorly ; it has but three tubercles while the succeed- 
« b 
Figdre 12. Chiro.v pUcaltis, Cope, one and a halftimes natural size ; a, viewed from below, palate with den- 
tition, three premolars and two molars in snfu; b, viewed from the outer side. After Cope. 
ing smaller premolars have four. The tubercles are conic, compressed and faintly 
grooved as in Bolodon.. The molars have each two complete and one half-row of 
tubercles. The first molar has two conic tubercles in the outer half-row, six in the 
mid-row and seven in the inner row. The tubercles are conic and separated by valleys, 
not by grooves; the inner face of the crown is smooth The second molar has the half- 
row on the inner side ; the mid and outer rows, have eight tubercles each, separated 
by grooves apparently indicating fore-and-aft wear. 
Several interesting resemblances will be noted between this and the Bolodon 
series. Chirox seems to be transitional in the structure of its molars, between the two 
and three row type, the additional half-row appearing to arise from the cingulum, but 
the premolars both ■ in form and number are very similar to those of Bolodon, with 
’ Proc. Amer. Phil. Society, p. 321, 1883. Also, Amer. Naturalist, June, 1887, p. 566. Professor Cope places 
this in a new family, the Chirogidx, but I tbink it may for the present be retained in the Bolodontida;. 
