R. L. Moodie — Coal Measures Amphibian. 509 



Art. XXXI. — A Coal Measures Amphibian icith an Osseous 

 Tarsus ; by Roy L. Moodte. 



There are known at present eighty-eight species of Amphibia 

 from the Coal Measures of North America, representing seven- 

 teen families and five orders. These forms were already 

 highly specialized and diversified into distinct geographic 

 groups, the members of which are not generically related. 

 This wide diversity of structure among the earliest known 

 faunas of air-breathing vertebrates is intensified by the fact 

 that one species of this number has an osseous tarsus; which, 

 in other forms, was apparently hyaline cartilage and left ho 

 impress of its structure in the rock or coal. A species, there- 

 fore, showing such an anomalous Condition is well worthy of 

 special consideration, and it is proposed in this place to give 

 an account of the "oldest known" amphibian tarsus 45 ", and to 

 add what little is to be known of the anatomy of the verte- 

 brate possessing this highly unusual foot. 



The only known specimen of this anomalous amphibian is 

 incomplete, representing the posterior half of the skeleton and 

 an abundance of ventral scutellse or calcified myocommata. 

 The block of coal containing these interesting remains is from 

 Linton, Ohio, and is preserved in the geological collections of 

 Columbia University, from which institution Professor Gra- 

 bau has very courteously forwarded it for study. 



Ichthycanthus platypus was described by Copef from the 

 Linton, Ohio, Coal Measures ; locating it doubtfully in the 

 Permian genus Eryops, on account of the unusual condition of 

 the tarsus and reconsidering a former decision in favor of a 

 Coal Measures genus, Ichthycanthus.^. In this disposition of 

 the species into the Permian genus he is followed by Hay§ ; 

 but Baur|| regarded the form as a member of the Coal Meas- 

 ures genus, Ichthycanthus, after commenting on the later defi- 

 nition by Cope (f). The type of the genus Ichthycanthus, to 

 which Cope ($) first allied the species under consideration, is 

 /. ohiensis, a supposed amphibian from the Coal Measures of 

 Linton, Ohio, founded on incomplete material. There is no 

 relationship indicated between Ichthycanthus and the species 



*Bam\ George: Amer. Natl., 1886, p. 173; Zool. Anz., No. 216, 1886. 

 At this time Archegosaurus was the earliest known amphibian form having 

 an osseous tarsus. 



fCope, E. D., Trans. Amer. Phil. Soe., 1888, p. 289, fig. 1. 



% Cope, E. D., Proc. Amer. Phil. Soc, 1877, p. 574. 



£Hay, O. P., Cat. Fossil Vert., Bull. U. S. G. S., No. 179. 



|| Baur, George : Beitrage zur Morphogenie des Carpus und Tarsus der Ver- 

 tebraten, Th. I, p. 16. Jena (G. Fischer), 1888. 



