510 R. L. Moodie — Goal Measures Amphibian. 



Fig. 1. 



tm 



of Eryops ; in fact, it is not possible to find on the specimen 

 all the characters indicated in Cope's figure (f p. 509, fig. 1) on 

 the basis of which he proposed to place the species in the 

 Permian genus. 



The majority of the American Coal Measures Amphibia were 

 small and the form under consideration is no exception. The 

 animal when alive probably did not 

 measure over eight inches in total 

 length, and the structures, which are 

 preserved in the block of coal fortu- 

 nately rescued from the coal mine dump, 

 JekS indicate a very active habit of life, re- 



calling the lizards of the present day. 

 The femora are strikingly reptilian in 

 appearance, as are also the ungual pha- 

 langes. The form combines in an un- 

 usual and remarkable degree reptilian 

 and amphibian characteristics. The 

 leg bones, the pelvis, the tarsus are all 

 strikingly reptilian, but the phalanges 

 in their arrangement of elements is so 

 typically amphibian that if we had no 

 other means of diagnosis we would in- 

 cline to locate this Coal Measures spe- 

 cies among the Amphibia. The leg 

 recalls in its structure that of another 

 Coal Measures species, Eosauravus copei 

 Fig l. Left leg and pel- Williston * which is, however, clearly a 



vis ot Eosauravus copei ,-, fil 1N -irn m j.i • 



Williston, from the Coal reptile (fig. 1). While there IS a gen- 

 Measures of Ohio, x 1. eral degree of similarity between the 

 Original preserved in the f 00 t structure of Eosauravus copei and 

 United states National Mn- lcU hycanthus platypus,^ there are 

 very great differences in the phalan- 

 geal formula and the arrangement of the tarsal elements. 

 These differences are clear, and indicate a separation of the 

 species into distinct classes. The phalangeal formula in the 

 Eosauravus 2-3-4-5-4, is typically reptilian ; while in the Ichthy- 

 canthus, 2-2-3-3-3 it is amphibian. The tarsus of the Ichthy can- 

 thus is amphibian in the presence of an intermedium, but this 

 is very small and the remaining tarsal structures have nothing 

 which might not be found in an early reptile. There may be 

 a single or even two centralia in the reptilian tarsus among 

 the early forms. 



The amphibian nature of the species having thus been estab- 

 lished, it remains to give a detailed account of its skeletal 



* Williston, S. W., Journ. Geo!., xvi, p. 295, figs. 1-2, 1908. 



