Horizon and locality: Linton, Ohio, Coal Measures.
The general appearance of the species of Pleuroptyx is that of the Molgophis, so far as known, but nothing resembling the peculiar structure of the ribs is seen in any other. There is no assurance that the genus is distinct from Molgophis.
Parts of two individuals express the typical characters of this species, while a third only differs in being considerably smaller. A fourth may very probably be referred here, and another, bearing several elements of a leg, should be most likely associated with the last mentioned.
The ribs are considerably narrowed near the head, and appear to possess a low tubercular process some distance below it. The shaft is curved throughout; the laminar expansion is quite thin; while the distal end is expanded and concave, perhaps for the attachment of cartilage, although no trace of this remains on the shale. The neural spines have short bases, oblique anterior and nearly straight posterior borders, with obtuse extremity. I perceive no essential difference in the smaller specimen, which is one-third less than the types.
The limb is appropriate in its proportions to the present species, and may be described in this place. The first segment is one-third longer than the second, and has a transversely expanded head. The shaft is stout, the distal extremity not expanded and concave. The second segment is stout, more expanded proximally than distally, the proximal end truncate and slightly concave. A bone, much displaced, lies near it, and is probably ulna or radius; it is as stout as the first, the end not expanded. Of metatarsals there are 2, three-fifths the length of the second bone of the leg, and of phalanges 2, of 2 digits each. The proximal are three-fourths the length of the metatarsals, and indicate elongate toes. The obverse of the specimen is preserved, and contains no additional toes or phalanges.
Fig. 33.—Forelimb of a member of the Molgophidæ, possibly Pleuroptyx clavatus Cope. × 0.75.
| Measurements of the Type of Pleuroptyx clavatus Cope. | |
| mm. | |
| Length of vertebral centrum | 14 |
| Depth of a vertebral centrum | 9 |
| Depth of entire vertebra | 22 |
| Length of neural spine | 8 |
| Height of a neural spine | 6 |
| Length of a rib on the curve | 42 |
| Width of a rib at ala | 9 |
| Width of a rib at extremity | 5 |
| Length of first segment of leg | 38 |
| Length of second segment of leg | 24 |
| Length of metapodial bone | 10 |
| Length of first phalanx | 7 |