2. Scales of Cercariomorphus parvisquamis Cope, a microsaur from the Ohio Coal Measures. × 10. Original in American Museum of Natural History.

3. Type specimen of Cercariomorphus parvisquamis Cope, from the Ohio Coal Measures. Original in American Museum of Natural History. × 0.75.

The femur is gradually expanded to the extremities. Proximally there is a trochanteric ala, besides the obtuse head. Distally the condyles are well distinguished, 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 distinct; 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 intermedium coössified. The tibiale is subtriangular. There are five distinct phalangeal 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 digitata. Cope (Trans. Am. Phil. Soc., XVI, 289, fig. 1, 1888) contributed the following note on Ichthycanthus platypus:

"A reëxamination 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 Eryopidæ. 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, Stereosternum tumidum Cope; giving five elements in the distal tarsal row. There is but one centrale and no intermedium. Two fragments of caudal vertebræ adhere to the specimen."

Measurements of Ichthycanthus platypus Cope.

mm.
Length of 10 dorsal vertebræ 45
Length of 15 caudal vertebræ 55
Length of centrum of a dorsal 3.8
Total elevation of a posterior dorsal 14
Length of femur 32 Length of first digit 10
Diameter of femur medially 4.5
Diameter of femur distally 8.3
Length of fibula 18
Diameter of fibula proximally 7
Width of sole at second row of tarsal bones 17
Length of foot to end of third digit 31
Length of third digit 22
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, representing the posterior half of the skeleton, and an abundance of ventral scutellæ 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 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 Permian genus he is followed by Hay ([317]); but Baur ([28]) regarded the form as a member of the Coal Measures genus Ichthycanthus, after commenting on the later definition by Cope. The type of the genus, Ichthycanthus, to which Cope first allied the species under consideration, is I. ohiensis, a supposed amphibian from the Coal Measures of Linton, Ohio, founded on incomplete material.