20 HYPOSAURUS. 



sand in the vicinity of Blackwoodtown, Camden County, N. J. The specimens are 

 very friable, in consequence of which tliey have been much mutilated smce their 

 discovery. They consist of portions of three cervical, as many dorsal, and five 

 caudal vertebrfe, a basilar bone, four croAvns of teeth, the greater part of the shaft 

 of a femur and fragments of several other long bones and 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 

 vertebrse, 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 vertebra;, 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 III, 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 foveae. 



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 Mosasaunis and tlie allied Genera, p. 9. 



