T^.NrODONTA. 
157 
This species is dedicated to Prof. Hermann Bnrmeister, director of the 
museum of Buenos Ayres, who has studied the Mammalia of the deposits 
of the Pampas, and given us an excellent account of their osteology. 
TiENIODONTA. 
The characters of this group, already pointed out,* are most distinctly 
seen in the teeth which are supposed to be superior incisors. Unfortu¬ 
nately, they have not yet been found in place in the cranium; but their 
association with a Rodent type of inferior incisors, which have been found 
in place in the mandible, confines us to the alternative choice between 
superior incisors and canines. From the small size or absence of 
inferior canines, a similar character may be inferred for the superior denti¬ 
tion. 
The superior incisors present two bands of enamel, an anterior and a 
posterior. They are compressed in form, the sides presenting a surface of 
dentine or cementum. Attrition produces a truncate or slightly concave 
extremity. The inferior incisors are Rodent-like. 
Two families represented this suborder in the Eocene period in New 
Mexico. The first or Ectoganidce possess molar teeth with several roots. In 
the CalamodontidcEj each molar has a simple conic fang. But one genus of 
each famil}^ is known. In Calamodon, the deficiency in enamel is supplied 
by a deposit of cementum. 
The type of superior incisors characteristic of this division is unknown 
elsewhere among Ma?nmalia. It is intermediate between the usual type and 
that of the'JRodentia, but it is not, therefore, evident that it represents a 
stage m the process of differentiation of the latter order. This is rather 
seen in such incisor teeth as those of Estlionyx. The great reduction in the 
extent of the enamel investment is an interesting approximation to the 
Edentata, where this substance is altogether wanting. The reduction is 
greatest on the adjacent sides of the molars; it has a little greater extent on 
the inner side, while it extends as a band on the exterior side, so that in w^orn 
teeth this surface alone remains. In addition, there are a heavy cementum 
* Proc. Acad. Phila., March, 1876. 
I 
