Case, Annals Carnegie Mus., IV, p. 234, pl. 59, 1908.
A dorsal vertebra is very probably from this genus. The specimen consists of a nearly perfect vertebra, lacking only the anterior zygapophysis and the upper portion of the neural spine ([plate 18, fig. 2]). It shows no character that would warrant its separation from the genus, and indicates a medium-sized individual. The zygapophyses have clean-cut articular faces. The pleurocentra are thickened above, with just well-defined articular faces, which were applied to faces on the neural arch posterior to the origin of the transverse process. The intercentrum is of the familiar halfmoon-shape, thick and heavy below, and thinner toward the extremities; the anterior edge is marked near the top by the indentation found on the intercentra of Eryops.
Height of the vertebra from the middle of the lower face of the intercentrum to the middle of the neural canal, 0.035 m.; width of intercentrum 0.026 m.
The second recognizable specimen is a neural spine from the caudal series. This is without question a portion of the skeleton of an Eryops. Similar spines were described by Cope as Eryops (Epicordylus) erythrolithicus, but later discoveries seem to show that similar characters occur in other species of the genus as well. The apex of the spine is bifurcate; the space between extremities is concave and perfectly smooth; below the sides of the spine are rather rugose and marked with ridges. The lower portion of the spine is elongated anteroposteriorly and the edges are marked with sharp, double ridges.
Three ribs also belong, in all probability, to the genus Eryops. The head of each rib is broad and the articular edge is divided between two faces which meet at an angle somewhat greater than a right angle; the two faces are continuous. The shaft is somewhat flattened and in the undistorted specimens is gently curved. The length of the largest rib is about 0.07 m.
Other than these specimens there are several small intercentra ([94]) and the neural spine of a caudal vertebra from some undetermined amphibian.
Family MACRERPETIDÆ Moodie, 1909.
Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix, fig. 1, 1909.
It has seemed necessary to propose a new family for the reception of the single species Macrerpeton (Tuditanus) huxleyi Cope. The characters exhibited by this species are so different from those offered by other members of the Carboniferous Microsauria that it is clearly distinct. In its cranial characters and the position of the orbits it approaches most nearly to Eryops megacephalus Cope from the Permian of Texas. In some of its characters the present form shows a similarity to Dasyceps bucklandi Lloyd ([324]), from the Permian of Kenilworth, England; more especially is this similarity found in the form of the skull, the size and shape of the teeth, and the posterior position of the orbits, and their wide removal from the border of the skull. Only a fragment of the skull has hitherto been known, but repeated study of this fragment ([123]) has disclosed the wide diversity ([462]) of its characters. An almost complete skull, described below, substantiates the characters based on the fragment. Another species is here added to the genus, based on a portion of a mandible and a portion of the skull.
The family, Macrerpetidæ, may be defined ([465]) as follows: