20 HYPOSAURUS. 
sand in the vicinity of Blackwoodtown, Camden County, N. J. The specimens are 
very friable, in consequence of which they have been much mutilated since their 
discovery. They consist of portions of three cervical, as many dorsal, and five 
caudal vertebra, a basilar bone, four crowns of teeth, the greater part of the shaft 
of a femur and fragments of several other long bones aa ribs, an astragalus, two 
phalanges, and portions of four dermal scales. 
In all the vertebral specimens the articular faces of the bodies are slightly con- 
cave, the anterior being more deeply depressed than the posterior. The cervical 
vertebrae, the best preserved of which is represented in Fig. 1, Plate IV, have their 
body nearly two inches and three-quarters long, with the form and proportions 
corresponding with those of the specimen previously described. The vertebral 
arch and canal are like the same parts in the Alligator. The spinous process, 
partially preserved in one specimen, ascends from a base extending the breadth of 
the arch and rapidly narrows as it rises. 
The dorsal vertebrae belong to the posterior division of the series. The best of 
the specimens, represented in Figs. 4, 5, Plate IV, has the body about two and a 
quarter inches long, and of slightly greater depth and less width anteriorly. 
The caudal vertebrae, Figs. 8, 9, 10, Plate IV, are short in relation with their 
depth and breadth. Their body is sub-cuboidal, with the articular ends slightly 
oblique; and they are provided with strong abutments for the articulation of sub- 
vertebral arches or chevron bones. The body of the best preserved specimen, Figs. 
9, 10, is about two inches and a quarter long, a trifle over two inches in depth: 
posteriorly, and less than’ two inches in width in the same position. 
The isolated basilar bone has its condyle nearly two inches wide at base, and a 
little over an inch in depth. 
The greater part of the shaft of a femur, Fig. 4, Plate IIT, is rather more than 
five inches in circumference at the middle, and is pervaded its entire length by a 
large medullary cavity. 
The astragalus measures two inches and a quarter in its long diameter, twenty 
lines in its short diameter, and is thirteen lines thick. 
A last ungual phalanx is nearly two inches in length. 
The dermal plates, of which two are represented in Figs. 11, 12, Plate IV, are 
without carina or tubercle, gradually thin away towards the margins, and are im- 
pressed by a comparatively few large and deep fover. 
The teeth, which accompanied the bones just described, represented in Figs. 
18-21, Plate III, are curved conical, compressed from without inwardly, and have 
their external and internal surfaces defined by an acute ridge. They are not fluted 
as in the specimens previously described, and were it not for their association might 
readily have been supposed to belong to a different animal. They are longitudinally 
wrinkled, especially near the base of the crown, and more internally than externally. 
The teeth described and figured by Dr. R. W. Gibbes, in the second volume of 
the Smithsonian Contributions to knowledge,’ supposed to be characteristic of a 
+ Memoir on Mosasaurus and the allied Genera, p. 9. 
