No traces of fore limbs have been detected in the numerous specimens, but elements of hind limbs are preserved. In one of these the femur is a small bone, contracted at the middle. The form of the body is snake-like.
There were probably from 75 to 100 vertebræ in a single animal. The form may be well compared to the modern Amphiuma so far as appearances are concerned; structurally they are widely separate. This species is one which is peculiarly characteristic of the Linton fauna.
| Measurements of Ptyonius pectinatus Cope. Nos. 107 and 1094 G, American Museum. | |
| mm. | |
| Length of specimen | 137 |
| Length of skull | 26 |
| Posterior width of skull | 8 |
| Interorbital width | 3 |
| Diameter of orbit | 1.5 |
| Vertical expanse of vertebra | 6 |
| Width of neural fan | 2 |
| Diameter of pedicel | 1 |
| Measurements of a small jaw, No. 8555 G, American Museum. | |
| mm. | |
| Length of jaw | 15 |
| Greatest width | 1.5 |
| Length of tooth | 1 |
| Measurements of specimen No. 4438, U. S. National Museum. | |
| mm. | |
| Length of specimen | 65 |
| Length of skull | 22 |
| Width of skull | 6 |
Cope, Proc. Am. Phil. Soc., p. 177, 1871.
Cope, Geol. Surv. Ohio, II, pt. II, p. 376, pl. xxviii, fig. 1, 1875.
Type: Specimen in the American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures.
The species is represented by the opposite halves of a single specimen, which includes only the cranium and anterior half of the body. The fan-shaped neural spines commence but a short distance behind the line of the pectoral shields. They are low, with a few coarse ridges, the margin being entire. The abdominal rods are delicate and hair-like. The interclavicle is oval, with a few radiating crests, which originate at the center; in the areas behind there are a few scattered tubercles. The clavicles are ridged near the margin.
The cranium is lanceolate in form, and the bones of the dorsum are marked with a few raised points and ridges. The species is about the size of Ptyonius pectinatus Cope, and differs, apparently, from that species in the rather insignificant character of a narrower interclavicle and in the ornamentation of the same. Dedicated to Professor Alexander Winchell, of the University of Michigan.