SYSTEMATIC REVISION 29 



Eryops megacephalus Cope. 



Cope, Proc. Am. Phil. Soc, vol. xvii, 1877, p. 188; Am. Nat., vol. xviii, p. 29. 

 Broili, Paleontographica, Bd. xlvi, 1899, s. 61. 



Type: The same as the genus. 



Original description: "The cranium has a subtriangular outline, with 

 the sides a little longer than the base, and the apex (muzzle) very obtuse. 

 The profile is elevated behind, and the sides slope steeply to the mandible; 

 the slope of the muzzle is rather steep, but less so than that of the cheeks. 

 The extremity of the snout is broadly rounded and depressed and overhangs 

 the mandible. The supraoccipital outline is concave, and the epiotic angles 

 only moderately prominent. The quadrate bones extend far posteriorly, 

 and are horizontal above at their distal extremities. The orbits are nearly 

 round, although somewhat wider than long, and they are directed equally 

 outwards and upwards. The inner margin is slightly flared upwards, and 

 it terminates anteriorly and posteriorly in a slight tuberosity, at the junction 

 with the canthus rostralis and temporal ridge respectively. 



"The orbit occupies the anterior portion of the posterior third of the 

 length of the skull, including the epiotic angles; and its long diameter is one- 

 seventh that of the skull from the epiotics to the muzzle inclusive. The same 

 diameter is about half the interorbital width. The parietal region is plane, 

 the frontal gently concave, and the muzzle depressed convex in cross-section. 

 The face in front of the orbit is concave below the canthus rostralis. The 

 nostrils are not large, and are subround. They are widely separated, being 

 nearer the maxillary border at its junction with that of the premaxillary 

 than to the median line. The mandible is shallow and not very stout. Its 

 inferior border rises from below a point a little in front of the fundus of the 

 epiotic sinus to the angle, which is at the quadrate articulation. Symphysis 

 short. 



"The sculpture of the anterior portion of the muzzle is coarsely punctate; 

 on the posterior portions of the upper and lower jaws it is ridged and pitted. 

 Most of the upper surface of the skull is still covered with a thin layer of the 

 matrix so that the sculpture and the character of the lyra, if any there be, 

 remain unknown. 



"The teeth, as has been observed, are not visibly grooved, but the char- 

 acteristic feature of the group may be represented by numerous delicate 

 crack-like lines, which one sees on the basal portions. These, however, resem- 

 ble the result of weathering. The sections of all the teeth would be round, 

 but for the cutting edges, which are not very prominent. In addition, the 

 premaxillary teeth are coarsely fluted on the median half of their length. 

 The fluting is not visible on an antero-lateral mandibular tooth, nor on a 

 posterior maxillary tooth. The microscopic structure of the teeth is not yet 

 investigated. 



"The bodies of the vertebrae have concave sides and a sub-round sec- 

 tion. The neural spines terminate in an obtuse enlargement. Many of the 

 characters of the vertebral column are yet concealed in the matrix. The 

 distal portions of the ribs are straight, cylindric, and become stouter at the 

 extremity. 



