Q 
1872.] 483 [Cope. 
one of its margins, a rod-like element projects. Its total length is about 
four feet, of which the acetabular sinus measures about 8.10 inches. 
A short bone pertaining to the limbs has the articular surfaces at a 
strong angle to each other, hence the shaft is twisted. It is deeply 
grooved on one side near the extremity. The other extremity bears a 
rather flattened hour-glass shaped articular face, and below it on one 
angle is a crest. The convexity of the surface is not great, and this 
extremity resembles that of a Dinosaurian or Crocodilian reptile. Its 
length is, however, only eight and a quarter inches ; apparently too small 
for a humerus, though this is not certain, while it is decidedly too small 
for a metatarsal of such an animal. 
From the above description, it is evident that the animal of Black 
Buttes is a Dinosauran reptile, the characters of the sacral and iliac 
bones alone sufficing to demonstrate this point. If the reader will 
compare the measurements given for species of this group already known, 
he will observe that those of the present animal exceed those yet described 
from North America. It is possible that if the corresponding parts of 
Hadrosaurus tripos, Cope, or Thespesius occidentalis, Leidy, are dis- 
covered, they may approach it. 
It is thus conclusively proven that the coal strata of the Bitter 
Creek Basin of Wyoming Territory, which embraces the greater area 
yet discovered, were deposited during the Cretaceous period, and not 
during the Tertiary, though not long preceding the latter. It ap- 
pears that the forests that intervened between the swamps of epochs, 
during which the coal was formed, were inhabited by these huge mon- 
sters. That one of them laid down to die near the shore of probably a 
brackish-water inlet, and was soon covered by the thickly fallen leaves of 
the wood. That continued subsidence of the level submerged the bones, 
which were then covered by sand. 
The form of the ilium differs very materially from that of Hadrosau- 
rus, and the vertebre are plane, thus differing from Thespesius. The 
limb bone is distinct from anything in Lelaps, which, moreover, probably 
resembles Thegalosaurus in its ilium. The present form recalls rather 
Cetiosaurus. As it is evidently new to our system, it may be called 
AGATHAUMAS SYLVESTRIS. 
NOTICES OF NEW VERTEBRATA FROM THE UPPER WATERS 
OF BITTER CREEK, WYOMING TERRITORY. 
By Epwarp D. Cops. 
(Read before the American Philosophical Society, September 19, 1872.) 
SyYNOPLOTHERIUM CANIUS. Cope. Gen. et sp. nov. 
This genus possesses the dental formula so far as known, I.}¢.5M ¢. in 
the only specimen with molars, the crowns are much worn, but in all, 
the antero-posterior much exceeds the transverse diameter, and consisted 
sr 
