Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/28

 24 THE EXTINCT BATRACHIA, REPTILIA COLOSTEUS FOVEA TITS, Cope. A very elegant sculptured median pectoral plate represents this 13:arm-lin It is larger than most of those of C. radiatus, but smaller than the one last described. The posterior and median parts of the plate are pitted to the number of six in five mm. The pits are separated by sharply defined ridges. They elongate towards the anterior parts of the plate, resembling elongate hexagons, and the ridges approaching radii, though not more elevated than the cross septa. The bevelled margins are rugose also, except at the edges. Length of the bone. 045 Greatest. width. .025 Width posterior margin, .021 From Linton, Columbiana County. Ohio. Prof. J. S. Newberry, Coll. No. 20. COLOSTEITS MA RSIII (tope. Sp. nov. This species is represented by a specimen of very much smaller size than either of the preceding. That it is nut the yonng of C. erassisantatus is indicated by the peculiar form of the dermal ventral scales. and by the greater anterior prolongation of the median ventral dermal bone. The specimen is lying on its back, displaying the ventral armature somewhat. disturbed, and broken throngb in some places, where the vertebrae and ribs would be discerned if they existed. The head is trailed abruptly to one side, and is apparently right side np. Several of its elements are scattered on adjacent portions of the block. 'rhe head is of an elongate lanceolate thrill. The upper surface of the frontal bones is punetate-rugose in relief; with short radii towards the margin. The distal two-thirds of the mandible is narrow wedge-shaped ; the external :nlace is coarsely pitted. There are no teeth preserved. The sntures of the cranial bones are of the scplamosal type or fish-like. The three thoracic shields are considerably displaced. The lateral are snbtriangtilar, and are strongly ridged towards the inner margin. The median shield is short spatnlate, the narrow portion directed anteriorly ; the posterior rounded. It is coarsely pitted medially. and coarsely and strongly radiate ridged to the margin. Immediately behind these plates the dermal armature commences. It consists of elongate, narrow, subeylindric scales, which are arranged end to end, in series which meet on the median line, converging anteriorly, as in the other types here described. At. first sight they resemble the long rod-like pieces of (Estocephalus, and careful examination is needed to detect the interruptions caused by the sutures of the sealer:. The latter are several times as long as wide, and appear to be terminated by oblique faces as in the typical species. The trace of limbs is only seen in a short impression resembling that of :t humerus behind the thoracic buckler. Nothing can be found pertaining to posterior limbs, but sonic laminae and impressions in the position of pelvis, but not immediately connected with the other portions of the skeleton, may belong to the latter arch. Measurements. lllf Length of body to buckler, 4.2 Width of ventral armature. .8 Impression of humerus. (or coracoida .2 Length median thoracic plate, 115 Width " bC .51 Length fragment under jaw, .75 Depth do. at middle. .15 -Width .29 end muzzle, This species, like the preceding. is from Dr. Newberry's collection, (No. 13,) and from the Linton coal bed, South-eastern Ohio. I have dedicated it to Prof. Othniel C. Marsh. Professor of Palaeontology in Yale. College. Connecticut.