(Cope. 
powerful offensive dentition. The jaws were stout, the dentary bone 
very deep. The teeth in a single row in all the bones, but of irregular 
sizes. There are two or three very large canines in each maxillary, and 
one in the premaxillary, three or four in the dentary separated by an 
interval. The lack of coronoid bone and many other characters show 
that it should be referred to the order Isospondali, and is probably allied 
to the herring and the Saurodontidae. The vertebre are grooved, and 
there .is a basi-occipital tube but little developed. The teeth are simple 
cylindric conic, with smooth enamel, and project two inches above the 
alveolar border, and each descends an inch into ityalveolus. The species 
and genus are new to our palaeontology, and may be named Portheus 
molossus. It turned out on subsequent exploration to have been quite 
abundant in the Cretaceous seas. It was probably the dread of its 
cotemporaries 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 probably 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 articulation, 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 m argins, which appears to represent 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 measured eight inches and a half in length, and 
are very stout, indicating a length of limb of seven feet at least. The 
whole expanse would thus be twenty feet if estimated on a Chelonian basis. 
The proper reference of this species cannot now be made, but both it and 
the genuss are clearly new to science, and its affinities not very near to 
those known. Not the least of its peculiarities is the great tenuity of all 
the bones. It may be called Protostega 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. Remains of several species of Cli- 
dastes occurred at various points in the neighborhood of Fossil Spring. 
One was found in the side of a bluff fifty feet above the bottom of the 
cation ; Martin Hartwell exhumed another near the 0. 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 Olidastes 
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 
