The centra of the dorsal vertebræ are about as long as deep, and their sides are deeply concave; there are 4 anterior to the pelvis which are without ribs. The caudal vertebræ are robust, and 7, from the first, support a small tubercle-like diapophysis. The chevron bones are short and acuminate; the neural spines are a little shorter, narrow, and truncate, and directed backwards at the same angle as the chevron bones. They are much reduced on the eighteenth caudal vertebra, where the chevron bones are considerably longer. The abdominal rods are quite slender. The hind limb is quite stout for this order. The femur is regularly expanded at both extremities, but the distal is deeply and openly grooved, distinguishing the condyles, while the proximal end is plane. There is no trochanter visible. The ulna and radius are well separated, and are three-fifths the length of the femur. There is a large fibular tarsal bone of a subquadrate outline. In immediate contact with it is probably the external digit with 5 phalanges or segments; the ungual is simply conic. The femur is as long as 5 dorsal vertebræ. The ribs have expanded, undivided heads, and extend to the abdominal armature. Measurements of the Type of Ichthycanthus ohiensis Cope. mm. Length of last 10 dorsal vertebræ 47 Length of first 23 caudal vertebræ 117 Length of a posterior rib 29 Length of a posterior dorsal vertebra 5 Length of twenty-second caudal vertebra 5 Length of femur 25 Proximal diameter of femur 8 Width of lower leg 9 Length of fibula 15 Length of tarsal bone 6 Length of digit 27 =Ichthycanthus platypus Cope.= Cope, Proc. Am. Phil. Soc., pp. 574, 575, 1877. Cope, Trans Am. Phil. Soc., XVI, p. 289, fig. 1, 1888. Baur, Beiträge zur Morphogenie des Carpus und Tarsus der Vertebraten, I Theil, p. 16, 1888. Moodie, Science, n.s., XLI, No. 1044, p. 34, 1915. Moodie, Am. Jour. Sci., XXXIX, pp. 509-512, fig. 2, 1915. Type: Specimen No. 79540, and obverse, Department of Geology, Columbia University. (Plate 23, fig. 1.) Horizon and locality: Linton, Ohio, Coal Measures. This amphibian is represented by the same portions of the skeleton as the preceding species, furnishing a good basis for comparison. It is very well preserved, displaying the characters, especially of the hind foot, which is almost entirely represented.