CHAPTER XXII. 



THE MICROSAUR1AN FAMILY ICHTHYCANTHID/C, FROM THE COAL MEASURES 



OF OHIO. 



Family ICHTHYCANTHID^E new family. 



This family is the most recently recognized group of the Linton fauna. Its 

 members, of which there are two known species, are distinct from all other Coal 

 Measures Amphibia in the possession of an osseous tarsus (483, 484), with its asso- 

 ciated reptile-like limb bones. There are preserved fine scutellae in a large patch 

 near the vertebral column. The vertebral spines are broad and heavy, with the 

 vertebral centra amphicoelous. 



Genus ICHTHYCANTHUS Cope, 1877. 



COPE, Proc. Am. Phil. Soc., p. 573, Feb. 3, 1877 (Pal. Bull. 24). 



BAVR, Beitrage zur Morphogeme des Carpus und Tarsus der Vertebraten, I Theil, p. 16, 1888. 



COPE, Trans. Am. Phil. Soc., xvi, p. 289, fig. I, 1888. 



MOODIE, Science, n. s., XLI, No. 1044, p. 34, 1915. 



MOODIE, Am. Jour. Sci., xxxix, pp. 509-512, fig. 2, May, 1915. 



Type: Ichthycanthns ohiensis Cope. 



The generic characters are derived from the characters presented by the pos- 

 terior dorsal and caudal vertebrae, with adjacent parts. The posterior limbs are 

 well developed, with distinct tibia and fibula, osseous tarsus, and 5 digits. Ribs 

 elongate, simple, curved. Abdominal armature consisting of bristle-like rods in 

 anteriorly directed chevrons. Dorsal vertebras not elongate, with simple neural 

 spines. Tail large, its vertebras ossified, and furnished with slender chevron bones 

 which terminate in a haemal spine. Neural spines broad and directed backwards ; the 

 caudal series somewhat resembling that of a fish. All the centra are amphicoelous. 



This genus differs from all those with enlarged and sculptured neural spines, 

 and from those with abdominal scutes. It is equally distinct from those without 

 ribs, abdominal rods, or limbs. It is possible that some of the species referred to 

 Tnditanus, in which these parts are unknown, may belong to it, or that it may be 

 established on a small species of Leptophractns, a genus known only as yet from the 

 skull. With our present imperfect knowledge of the Linton forms it seems best to 

 refer /. ohiensis and /. platypus to this distinct genus, Ichthycanthns. 



Ichthycanthus ohiensis Cope. 

 COPE, Proc. Am. Phil. Soc., 1877, p. 573 (Pal. Bull. 24). 



Type: Specimen in the American Museum of Natural History. 



Horizon and locality: Linton, Ohio, Coal Measures. Collected by Dr. J. S. 

 Newberry, in the summer of 1876. 



The centra of the dorsal vertebrae 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 vertebrae 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 



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