THE MICROSAURIAN FAMILY ICHTHYCANTHID^E. 173 



the external or fibular being truncate. The fibula is less than three-fifths the length 

 of the femur, and is expanded at both extremities. Two proximal tarsals are dis- 

 tinct; the one next the fibula is larger than the other and transverse suboval in 

 form. It has a median dividing ridge as though composed of fibulare and inter- 

 medium coossified. The tibiale is subtriangular. There are five distinct phalan- 

 geal tarsals. The toes are, in the order of their lengths, beginning with the shortest, 

 1-2-5-3-4. Their phalanges (including metatarsals) are, in the proper order, 

 commencing with the hallux, 3-3-4-5 ?-5, the distal end of the fourth finger being 

 lost. These bones are rather stout, and the unguals are simply conic. The form of 

 the foot is short and wide. The number of the phalanges is nearly similar to that 

 found in Amphibamus grandiceps, excepting that in that species the fifth digit has 

 but 4. They are more numerous on most of the digits in Sauropleura digitate. Cope 

 (Trans. Am. Phil. Soc., xvi, 289, fig. I, 1888) contributed the following note on 

 Ichthycanthus platypus: 



"A reexamination of the type specimen of this species from the Coal Measures of Ohio, 

 preserved in the Museum of Columbia College, New York, enables me to refer this species 

 to the Rachitomi. The neural spines are distinct, showing that it belongs, probably, to the 

 Eryopidse. As the skull is not preserved, I can not determine the genus positively, but 

 refer it for the present to Eryops. I append a figure of the posterior foot, which displays 

 the characters of the tarsus of this group for the first time. The number of tarsals is as 

 in a Theromorph reptile, except that two elements represent the cuboid bone as in the 

 reptile, Stercosternum tumidum Cope; giving five elements in the distal tarsal row. There 

 is but one centrale and no intermedium. Two fragments of caudal vertebras adhere to 



the specimen." 



MEASUREMENTS OF ICHTHYCANTHUS PLATYPUS COPE. 



mm. mm. 



Length of 10 dorsal vertebrae 45 Length of fibula 18 



Length of 15 caudal vertebrae 55 Diameter of fibula proximally 7 



Length of centrum of a dorsal 3.8 Width of sole at second row of tarsal bones 17 



Total elevation of a posterior dorsal 14 Length of foot to end of third digit 31 



Length of femur 32 Length of first digit 10 



Diameter of femur medially 4.5 Length of third digit 22 



Diameter of femur distally 8.3 Length of fifth digit 20 



The writer has had the privilege of restudying this interesting specimen and has 

 already (484) described the foot and tarsus, as follows: 



The only known specimen of this anomalous amphibian is incomplete, repre- 

 senting the posterior half of the skeleton, and an abundance of ventral scutellag or cal- 

 cified 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 Grabau very courteously forwarded it for study. 



Ichthycanthus platypus was described by Cope 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 Per- 

 mian genus he is followed by Hay (317) ; but Baur (28) regarded the form as a mem- 

 ber of the Coal Measures genus Ichthycanthus, after commenting on the later defi- 

 nition by Cope. 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. 



