Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/72

 66 THE EXTINCT BATRACHIA, REPTILIA The dermal plates are about the size of Holops obscurers, but have smaller pits, wider intervals, and one margin without pits, but smooth and thinned out. Lines. Width minus where tooth series turns from inner to outer margin, ]4.5 t interorbital space, articular facet of mandible, 19. Length dermal bone, 25. It is difficult to refer vertebrae to this species with certainty, as they resemble so closely those of Holops. The species is less abundant than those of the latter, and being found with them the vertebral, are easily confused. It is not impossible, for instance, that those referred to H. tenebrosus belong to this animal. as teeth of the latter were found near the same time and place. There have, however, come under my observation some vertebrae different from those of any of the Holopes, which correspond in size and rarity with the present crocodile. A description ix therefore appended. First—These are a fourth cervical vertebra, and sonic long bones, which were presented together to the Burling-ton County, N. J., Lyceum. and were procured at Gaskill's excavations near Birmingham in the same county. The vertebra differs much in form from other species here deseribed, and though absolutely larger than those of T. neocaesariensis, the neural arch was not coossified with the body, indicating the immaturity of the individual. The body is but slightly concave between the planes of the parapophyses, which are not at all directed down-wards ; the latter are very short, and their articular faces are directed posteriorly and outwards anteriorly, the posterior portions being connected by a high erescentoid ridge, whose anterior margin approaches within three lines of the rim of the articular enp ; behind. a weak median keel connects it with the body plane, which is sneeeeded by a prominent tuberosity close to the posterior shonlder. The anterior parapophysial artieular surface extends without constriction to the rim of the cup. The floor of the posterior half of the neural canal is broken away, revealing a wedge-shaped chamber, which extends posteriorly and outwardly nearly to the shoulder. In. Lin. Total length. 2 10. Length to shoulder, 2 3. Width of cur, 1 8. Vertical diameter of cup, • • • to edge of parapophysis, 1 2 0.75 Width between parapophyses near cup, is it it at posterior angle, 1 2 10. 1. Length from nost. angle parap. to shoulder, 1 1.25 Length from post. angle parap. to cup, 1 2.5 The radii of the median area of articulation are numerous, t8-1), fine and equal ; the transverse inn of the anterior area are also fine, thirteen in number. Portions of femur, tibia, humerus, ard ribs were in the same lot with the above described vertebra; they resemble the cervical vertebra in color and in the bright green of the matrix which adheres to them externally, as though they had been wet ; their size relates so as to render their appertainance to the same animal probable. They indicate an animal of large size. The shank of the femur is cylindrical at its middle ; the prominence of the anterior flexure is situated well below the head, while the head itself is not as broad as in some species (e. g. Crocodilus Liporcatns). An obtuse ridge runs from behind forwards and downwards across the outside face of the shaft, transferring the position of the steepest face from the back to the front aspect. On the inner face the troohanter is small, and the surface is swollen near the upper edge at the flexure. Compared with the shank of the femur of Hyposaurus rodgersi, the present is less depressed and lacks a longi-tudinal concavity, with obtuse elevated margins, near the superior flexure, which is characteristic of that species. For a considerable proximal portion of the femur, the medullary cavity is quite small ; at the middle it is lunch larger, and the walls quite thin : measurements are,