1872.] 467 [Cope. 
PANTOLESTES LONGICAUDUS. Cope. 
xen. et Sp. nov. 
This form is one of those mixed types which are so abundant in the 
Bridger Group. Its dental formula is M. 3, P. M. 3; ¢. 1, incisors un- 
known. The molars in the only specimen known are so worn as to pre- 
clude exact description. They evidently possessed anterior and posterior 
lobes, separated by a valley, which was most expanded on the inner side. 
The last molar exhibits a projecting keel posteriorly, which probably 
supported a small tubercle. The three premolars are all two-rooted and 
compressed in form. The last presents a crown composed of one large 
anterior compressed cusp, and a much lower posterior one. There is a 
slight cingulum in front. The canine is lost, but its alveolus indicates 
that it was a stout tooth. 
So far as the known dental structure goes, this genus resembles nearly 
the WNotharctus of Leidy (Limnothertum of Marsh), but possesses one 
premolar tooth less. 
The mandibular ramus is quite slender, and there is a large foramen 
below the first true molar. The masseteric fossa is pronounced. 
M. 
Length of dental series to canine.........-. eed eles 0.0280 
e SUNOCO IMOIHER fe 0c siee eae tite als olds syd seins .0140 
on (o sogGna Ce 0041 
Wadtbic = Ae .0030 
There were found associated with this jaw some caudal vertebra of 
very attenuated form, which point to the possession of a long tail by this 
animal. One of these displays six short processes arranged round the 
articular extremity, the neural arch not being completed. 
M. 
TiOnStH 6 fs5iees Te Ric EW van on esi caws toe 016 
‘Prowl AMEE is Oe ve A aces es eg elias .003 
Median ML es bea WS Pepe cuneate FS ra .0018 
PsEUDOTOMUS HIANS. Cope 
Gen. et sp. nov. 
This form is interesting as the only member of the Edentate order yet 
discovered in our earlier Tertiary formations. It is represented by a 
species of which a nearly perfect cranium is in my possession. This is 
about the size of an agonti, and is of a depressed form. It has a thin 
molar and zygomatic arch, but no postorbital. There is a large suborbital 
foramen. The dentition consists of two pairs of long curved teeth, hav- 
ing much the form and position of the cutting teeth of Rodentia. These 
are placed widely apart in the upper jaw, allowing space for the greater 
portion of the premaxillary between them. The mandibular cutters are 
less widely separated by a narrow prolongation of the symphysis. The 
exposure of the tooth is lateral, its direction nearly anterior. It projects 
anteriorly very little beyond the symphysis, and has a horizontal triturat- 
ing surface below the level of the latter. Neither pair of cutting teeth 
