0. C. Marsh—New Tertiary Reptiles. 299 
all in the Eocene beds of the Green River basin, first examined 
by the Yale party, in 1870, and found to contain so many new 
and interesting forms of vertebrate life.* In this extinct fauna, 
eptiles were particularly abundant, and among them were 
numerous Lizards, several species of which are here described. 
Thinosaurus paucidens, gen. et sp. nov. 
The present species is based upon the greater part of a skele- 
ton found, by the writer, in place. Portions of several other 
of the crowns attached to the inner wall of the jaw are muc 
expanded, and their sides furrowed, as in Heloderma. The 
orsal vertebree have the articular ball and cup transversely 
elliptical, and much inclined. The centra have their inferior 
surface very slightly concave longitudinally, and convex trans- 
versely. The articular faces for attachment of the nibs have 
* This Journal, vol. i, 1871, pp. 192, 322, and 447. 
