ON THK STIlUCTUKE AND CLASS fF'ICATION 
2;J4 
has a single main cusp and a posterior heel apparently supporting a low basal cusp, 
as in Peraspnlax. The molars have a single main, external cone, which is very 
slightly antero-verted, and has a distinct cingulum upon the outer face. The inter- 
nal face supports a median cusp which rises to about half the height of the main 
cusp, a slightly lower anterior cusp and a heel-like process posteriorly. The lower 
jaw is short and massive, with a deep mylohyoid groove reaching the symphysis. 
Note. — The molars of this genus resemble those of Peraspalax so closely as to 
leave little doubt of the family relationship between these genera, although 
Panrodon has but six, or at the most seven, post-canine teeth. The opposition of the 
Peralestes and Peraspalax cusps (see fig. 16 text) is probably such that the tip of the 
external cusp of a lower molar fits into the valley separating the cusps of an upper 
molar, and vice versa. 
Herbivorous Sub-Group. — The single family embraced in this sub-group is 
widely stjparated from those which we have been considering, by the unique character 
of the dentition. The inner aspect of the crowns is very similar to that of the Stylodon 
molars and the single specimen which represents this family was referred to this genus 
by Professor Owen. But the wearing surface of the crown is essentially different 
from that of Stylodon as it is wholly devoid of cusps and without any degree of 
trenchant function. The fangs are distihet and placed transversely and are in a line 
of modification which ends in growth from persistent pulps. The wearing pattern of 
<lentinc, traversed by ridges of enamel, resembles distantly that of the Rodents and 
more nearly that of the PhascolornyidcB, and we may infer that Kurtodem represents a 
class of animals which fed upon roots and other vegetable substances. The large size 
of the foremost tooth is, however, somewhat against this conjecture, unless it should 
prove to l>e not the canine but one of the lateral incisors. 
IV VJ i\ 1 1 xUJjliy 
.yfolars wit/ioiU cusps, with compactly placed trihedral columnar crotons. Wearing 
surMee flattened, with enamel ridges, indicating horizontal wearing action, as distin- 
gutsh^ from vertical. Two or three fangs set transversely. Premolars rudimentart, 
or sub-molariform. 
at present the single genns Kurlodon, of which only the 
mnx.llary dentition is known. It may be defined as above. 
usDorn,- 
AOO/. 
the cTnite Ind 'll 1 'a ’’"‘nV” " is small, placed closely behind 
canine and styloid. Behind this is a diastema followed by the rudimentary 
> Proc. Acad.. Phila., .Tune. 
•Proo. Acad., Phila., June. 
Athrodontidx, Syn. 
Aihrodony Syn. 
