Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/26

 00 THE EXTINCT BATRACIIIA, REPTILIA GNOCEPHALA. COLOSTEUS, Cope. This genus is proposed for Gauocephala, allied to Apateon ( Ardegoecotrus) but (liffer-ing as follows : There are no traces of vertebral centra or spines, or of ribs, in portions of six individ-uals preserved. No sclerotic bones can be found in one cranium partially preserved. There appears to be two pairs of very short limbs. The usual three sculptured pectoral bones are present, consisting of a rhombic medial, and a pair of half rhomboid laterals. The abdominal region is protected by series of scales which extend obliquely forwards to the medial line, where they meet, forming chevrons. They are closely approximated, and are composed of rhomboidal scales which have a convex external and internal face, in transverse section, and which overlap at the extremities, and are in contact by faces which are oblique in both the longitudinal and transverse directions. 'The exact form of the muzzle cannot be made out. It is, however, not elongate, nor yet of the broad rounded form of' Fellow Several teeth are preserved. There are two kinds, which occupy the margins of the maxillary and dentary bones. The anterior teeth appear to be longer than the posterior, though the latter are mostly broken oil Most of the teeth. are coarsely incised silicate for perhaps their basal half. Two long teeth behind their distal extremity of the clentale, are on the other hand very finely and sharply striate for their basal half; the tip is subcylindric, and very prolonged and acute. A small, dagger-shaped tooth near the base of one of the posterior, may be-long to the successional, or to a small outer series. A series, of four elevated tooth bases, with a broken crown, of much smaller size than those of the jaws belongs to the vomerine or a palatine series. The row is single and uniform. The superior face of the cranium is injured, but the component bones appear to have possessed a radiating sculpture of no great distinctness. The form of the body seems to have been long and fish-like, with little contraction near the limbs. Caudal extremity is not preserved. There vs ere probably two pairs of very weak limbs, of «inch three metacarpals of the anterior are preserved. A narrow longi-tudinal hone extends posteriori) from the lateral pectoral bone. Its extremity is broken, but a flat, narrow, longitudinal bone, with a dilated extremity curved outwards, may be-long to it, or be the humerus. I find no distinct traces of branchial arches. '['he affinities are thus obviously to Apateon, and it is not beyond possibility that future investigations may prove it is the same, though this is not probable at present. Portions of seven individuals of one species, and of one individual of another, were discovered by John S. Newberry at Linton, Ohio. They differ as follows:.