Moodie, Am. Jour. Sci., XXXIX, pp. 509-512, fig. 2, 1915.
Type: Specimen No. 79540, and obverse, Department of Geology, Columbia University. ([Plate 23, fig. 1.])
Horizon and locality: Linton, Ohio, Coal Measures.
This amphibian is represented by the same portions of the skeleton as the preceding species, furnishing a good basis for comparison. It is very well preserved, displaying the characters, especially of the hind foot, which is almost entirely represented.
Several features distinguish it from the I. ohiensis, one of which is of more than usual value if correctly indicated by the fossil. There are 10 vertebræ from the anterior end to the sacrum preserved in place, and none of them supports a rib, nor are there any ribs visible anywhere on the block of shale. I suspect that they exist on more anterior vertebræ, or may have been displaced to a more anterior position than they normally occupy. The abdominal chevrons are more anterior in position than are those of the I. ohiensis. The hind legs are longer than in that species; in this one the femur equals 7.5 vertebral centra in length. The external digit, on the other hand, while bearing 5 phalanges, is distinctly shorter. The fibular tarsal is of a transverse oval, not quadrate, form.
The dorsal centra are shorter and deeper than long; the neural arches are elevated, with short but distinct zygapophyses, and a flat, subquadrate, superiorly truncate, neural spine. They bear short, vertically compressed diapophyses near the base of the arches. The neural spines of the caudal vertebræ become rapidly more slender, and also diminish in length, while the zygapophyses are continued to the fifteenth vertebra. The chevron bones are slender, and inclose a moderate hæmal opening.
MOODIE
1. Photograph of the type specimen of Pelion lyelli Wyman, from the Ohio Coal Measures. Supposed to represent the ancestral form of the Salientia. × 2. Original in American Museum of Natural History.