794 NATURAL HISTORY MISCELLANY. 
Cretaceous seas. It was probably the dread of its cotempora- 
ries among the fishes as well as the smaller saurians. 
On another occasion we detected unusually attenuated bones 
projecting from the side of a low bluff of yellow chalk, and some 
pains were taken to uncover them. They were found to belong 
to a singular reptile of affinities perhaps to the Testudinata, this 
point remaining uncertain. Instead of being expanded into a 
carapace, the ribs are slender and flat. The tubercular portion 
is expanded into a transverse shield to beyond the capitular artic- 
ulation, which thus projects as it were in the midst of a flat plate. 
These plates have radiating lines of growth to the circumference, 
which is dentate. Above each rib was a large flat ossification of 
much tenuity, and digitate on the margins, which appear to repre- 
sent the dermo-ossification of the tortoises. Two of these bones 
were recovered, each two feet across. The femur resembles in 
some measure that ascribed by Leidy to Platecarpus tympaniticus, 
while the phalanges are of great size. Those of one series meas- 
ure eight inches and a half in length, and are very stout, indicat- 
ing a length of limb of seven feet at least. The whole expanse 
would thus be beyond twenty feet if estimated on a Chelonian 
basis. The proper reference of this species cannot now be made, 
but both it and the genus are clearly new to science, and its affini- 
ties not very néar to those known. Not the least of its peculiari- 
ties is the great tenuity of all the bones. It may be called Proto- 
stega gigas. 
The greater part of a large Liodon proriger Cope was found 
scattered over a denuded surface at one point, his huge, truncate 
bowsprit-like snout betraying his individuality at once. Portions 
of other examples of this reptile were afterwards found. Re- 
mains of several species of Clidastes occurred at various points 
in the neighborhood of Fossil spring. One (C. duw sp. n.) was 
found in the side of a bluff fifty feet above the bottom of the 
canon ; Martin Hartwell exhumed another near the C. cineriarum 
Cope almost complete. 
We subsequently left this locality and encamped at Russell 
springs on the Smoky Hill, twenty-six miles distant. On the way 
a large Clidastes of some forty or more feet in length was found 
lying on a knoll of shale, with the head displaying the palatal 
surface upwards. On the Smoky our explorations were attended 
with success. When we shifted camp, it was to go to Eagle Tail 
in Colorado, whence we returned again to Fossil Spring. The 
