Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/67

 AND AYES OP NORTH AMERICA. 6 1 is perhaps a posterior dorsal. It is but slightly curved, has a vertically broad oval section proximally, and a depressed trigonal one distally; there is little trace of a medullary cavity. Length, 0.23 Vertical diameter at distal third, 0.014 Do. from head to tuberele, 0.03 Transverse do., 0.155. I find no abdominal ribs, such as are abundant in the North Carolina specimen described on a preceding page. This speeies has been distinguished from B. prisons by the form of its caudal vertehne. The measurements given by Emmons and Leidy, of the other species, differ in the greater elongation of the vertebral contra. The length of the latter is in each case greater than the width of the articular face, instead of less. They are also smaller in all their dimensions. We shall not go very far wrong in estimating the length of this species on the basis of the gavial of the Ganges, as furnished by .Cuvier. This would give to the Deletion lepturus a length of about ten feet, and a habit stouter than that of the Crocodiles of the present day. This species was discovered by Chas. M. Wheatley, proprietor of the lead and zinc mines at Phrenixville, Penna. He obtained the remains from the "Bone bed" of the Trills, where exposed by the Phoenixville Tunnel of the Read-ing Railroad. This stratum is, according to Wheatley, 6 ft. 6 in. from the top of the series; 52 ft. 6 in. lower down is a strattun rich in plants and Saurian remains, and 95 ft. deeper occur bituminous shales with caprolites and bones. Clzt.0 C 0 ID I LI I.A. The constitution of the cranium in this order is very characteristic and peculiar. The basal cranial bones are forced backwards, so that they occupy a more or less vertical posi-tion, and the sphenoid is almost concealed in many. The quadrattun is immoveably embraced by the exoccipital, prootic and opisthotic. The pubes do not enter into the walls of the acetabulum as sin Mammalia and Reptilia, but originate from the inferior pelvic arch. The) form no common suture, but extend sub-longitudinally, thus differing from pubes generally. The latter relation of true pubes occurs among Reptiles only in Chelys, Pelomedusa galeata, and Sternotiuerus, among the Chelonia, and in Pterosauria. An anterior process from the ischium occupies the usual position of the oligin of the pubis, as a support for the latter. There are at least two well marked types in the class, defined as follows: Vertebrae procoelian, 1. e. with anterior cup and posterior ball ; the sphenoid bone little visible on the base of cranium. PROCOELI. Vertebrae concave or nearly plane at both extremities ; sphenoid bone with larger and more horizontal exposure on base of cranium. AMPHICOELL The only genus of Amphiectli known in this country is Hyposaiirus ; the Procoelian genera are the following: A The teeth composed of several enclosed cones of dentine. a The cervical vertobice with very rudimental or split h3papophyses. A large fossa of foramen issuing between the prefrontal and lachrymal bones of the face ; muzzle long, slender, teeth equal. THORA.COSAURITS. AMEHI. PHILOS°. SOC.-VOL. XIV. 16