342 
A MEMOIR UPON THE GENUS 
is nearly straight, slender and approaches very closely m form that oi D,pla,odon. 
Tl.e orbit is quite large and the great antero-poster.or extent of the orbital floor 
is characteristic of Tdmalotim-mm. The axial and appendicular skeletons are 
unknown. 
Synopsis of the Species of the Genus Telmatotherium. 
There are bnt three known species of this genus, wnth a number of interesting 
transitional varieties. 
1. Inferior diastema large T. hyognathus. 
2. Inferior diastema small. 
a. Superior premolar 2 with a rudimentaiy internal lobe T. cultridetis. 
b. Superior premolar 2 with a well developed internal lobe T. vahdiis. 
XELMATOTHEHiaM VALIDUS. 
I have already stated in my preliminary paper that the superior molars fig- 
ured by Cope' as belonging to P. valide7is should be really referred to this species. 
The fact that in this series of molars the second snperior preniolar has a well devel- 
oped internal lobe would include it under the specific characters of T. validtis. 
Considerable variation exists in the premolars of this species as regards their 
internal cingula, and I consider a complete or incomplete cingulum as having no real 
specific value, at least as applied to this subfamily. I have treated this character 
under the head of P. paludos^is, and showed its wide variation in that species. I 
still have another illustration of the wide variability in the character of the cingula 
in T. validiis. 
Dentition. — Most of the characters which I shall give for the dentition of T. cul- 
tridens will apply eqnally well to T. validus, so that it is only necessary to enumer- 
ate the specific characters which distinguish the latter from T. cnltridens. The teeth 
of T. validus are considerably larger than those of T. culPidens, especially the 
diameter of the premolars. The second premolar is much larger antero-posteriorly 
than that of T. mlb'ide^is ; it is provided with a large internal lolie and its internal 
basal cingnlnm is complete. These characters we see at once, esiiecially the 
largely developed internal lobe of premolar 2, are very different from those of T. 
cidtridens. The other premolars have high crowns and well marked vertical folds, 
the latter character being especially prominent on the external lobes of the last 
superior premolar. The last two superior premolars have slightly marked proto- 
conules and their internal cingnla are incomplete. In the series of the superior 
molars of this species figured by Cope all the premolars have conqdete internal 
cingula. The external cingula of all the true molars are not as strongly marked in this 
species as in T. cultridens, although in Cope’s examples the external cingula are more 
marked than in Marsh’s type sjiecimen. In contrast to the other species of this 
genus the intermediate conules are well developed. The first molar has a ivell 
developed protoconule ; the second molar has also this conule developed. The pos- 
'Tertiary Vertebrata, Plate LI, fig. I. 
