"Represented by a fusiform body which terminates in a long, slender, cylindrical tail, and which is covered with small subquadrate scales quincuncially arranged. No fins or limbs are preserved, and the form of the head can not be made out. Probably a portion of the skull is preserved. There are some scattered bodies in the body portion, which look like deeply concave vertebræ with the zygapophyses of batrachians. There are some linear impressions at one point, which resemble the bristle-like rods on many Stegocephali. They are so few as to be of little importance. The scales are like those of fishes. There are traces of segmentation in the axis of the long tail. "The position of this curious form is quite uncertain. It is quite different from anything observed hitherto in the American Coal Measures." =Cercariomorphus parvisquamis Cope.= Cope, Proc. Amer. Phil. Soc., 1885, p. 405. Moodie, Science, n.s., XLI, No. 1056, p. 463, 1915. Type: Specimen No. 2560, Newberry Collection, American Museum of Natural History. Horizon and locality: Discovered by Samuel Huston at the Linton, Ohio, Coal Mines. (Plate 21, figs. 3, 4; 24, figs. 2, 3.) The scales (Plate 24, fig. 2) in their present condition are entirely smooth. At a distance of 20 mm. from the base of the tail they are in 20 longitudinal series. At that point the transverse diameter of the body is 140 mm. The outline contracts rather abruptly to the tail, of which 66 mm. are preserved. The surface of the tail is obscured by a thin layer of carbonaceous matter not sufficiently thick to obscure scales, which are evident at distances of 16 mm., 43 mm., and 52 mm. from the tip. The scales on the tail are smaller than those on the body and are without markings of any kind. The anterior half of the body is depressed and distorted, but the remainder is well preserved and shows a fairly good outline of an apparently limbless body. An additional specimen (No. 8683 G, of the Newberry Collection, American Museum of Natural History) reveals no new facts as to structure, but serves to show that the body of the animal was long and slender (plate 21, fig. 4). The portion studied comes undoubtedly from the middle of the body. No limb elements are preserved. The scales are somewhat larger, especially toward the sides of the body, than in the type. The fragment measures 70 mm. in length by 18 mm. and 26 mm. in width. One of the largest scales measures 1 mm. in diameter. Measurements of Type. mm. Length of entire remains 180 Greatest width 22 Greatest width of undisturbed portion 15 Length of an individual scale .75 CHAPTER XIX. THE AISTOPODOUS MICROSAURIAN FAMILY PTYONIIDÆ, FROM THE COAL MEASURES OF OHIO. =Family PTYONIIDÆ Cope, 1875.= Cope, Geol. Surv. Ohio, II, pt. II, p. 357, 1875.