24 THE EXTINCT BATRACHIA, REPTILIA 



COLOSTEUS FOVEATTJS, Cope. 



A very elegant sculptured median pectoral plate represents this Batrachian. 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. 



M. 

 Length of the bone. .045 



Greatest width, .025 



Width posterior margin, .021 



From Linton, Columbiana Comity, Ohio. Prof. .1. S. Newberry, Coll. No. 20. 



COLOSTEUS MARSHII, Cope. 

 Sp. nov. 



This species is represented by a specimen of very much smaller size than either of the preceding. That it is not 

 the young of C. crassiscutafrus 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 through in 

 some places, where the vertebra? and ribs would be discerned if they existed. The head is turned abruptly to one 

 side, and is apparently right side up. Several of its elements are scattered on adjacent portions of the block. 



The head is of an elongate lanceolate form. The upper surface of the frontal bones is punctate-rugose in relief, 

 with short radii towards the margin. The distal two-thirds of the mandible is narrow wedge-shaped ; the external 

 surface is coarsely pitted. There are no teeth preserved. The sutures of the cranial bones are of the squamosal type 

 or fish-like. 



The three thoracic shields are considerably displaced. The lateral are subtriangular, and are strongly ridged 

 towards the inner margin. The median shield is short spatulate, 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, subcyhndric 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 scales. 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 a humerus behind the thoracic buckler. 

 Nothing can be found pertaining to posterior limbs, but some 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. MM. 



Length of body to buckler, 4.2 



"Width of ventral armature, .8 



Impression of humerus, (or coracoid,) .2 



Length median thoracic plate, 1-15 



Width " " " .51 



Length fragment under jaw, .75 



Depth do. at middle. .15 



Width end muzzle, .29 



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. 



