138 PALEONTOLOGY OF ILLINOIS. 



sentcd by the specimen. It may be a superior ethmoid plate, as in the frogs 

 Bwhorocxtes and others, or, more probably, a united or separate pair of free 

 frontal, as in Dactyletlira or Rana. There is no trace of the composition of 

 nasals and frontals, which occurs in the Gradientia, nor is such an arrangement 

 probable, in view of the regular elongate cuneiform outline of this singular 

 piece. A moderately distinct suture, crossing the front at the anterior third 

 of the interorbital space, which presents a regular convexity forwards, appears 

 to be the anterior border of the frontal; the latter can scarcely be an interorb- 

 ital plate of ethmoid, as it appears to unite behind by suture with the parietals. 

 There are bosses on the pre-frontal region, indicating pre-frontal or "lachry- 

 mal " bones, similar to those in Sceloporus and other Lacertilian genera. 



What may possibly be the coronal suture, since it appears to be too regular 

 to be a fracture, crosses the narrowest part of the interorbital space. It is a 

 zigzag, presenting posteriorly a median angle, and one on each side. The pos- 

 terior zygomatic arches are strong, and bound a cranial plane, which is broader 

 than long, and exhibits nearly parallel lateral outlines. The probably small 

 "crotaphite foramina" of the temporal fossae appear to have been roofed over 

 by perhaps the strong scales of the cranial integument. The quadratum is 

 convex externally, and is directed obliquely backward to opposite the occiput; 

 it is strongly concave in its posterior outline, indicating a large auricular 

 meatus. Whether this was covered by scales or by an exposed tympanic drum, 

 cannot be determined. The quadratoj ugale is broad and strong. The postorb- 

 ital arch is continuous with the quadratum; the breadth of the two equals the 

 frontal width. The angular process of the mandible is but little prolonged 

 beyond the quadratum. The maxillary is toothed, at least as far as opposite 

 the malar process. 



The dentition is pleurodont ; the teeth are only visible on the mandible and 

 the outer edge of the upper jaw; they are there of but one kind, small, closely 

 set, acute-conic, not compressed, hollow, and without any inflections of the 

 enamel. 



The integument of the head was squamous. The scales appear not to have 

 been imbricate, and were perhaps more dense on the posterior regions, where their 

 position is occupied by the white material mentioned in Prof. Worthen's note, 

 which has here a somewhat ganoid appearance. They were more elongate on the 

 muzzle. There appears to have been a distinct superciliary, and a postorbital row, 

 as well as a series on the border of the upper lip. A whorl of elongate scales, 

 arranged like the pieces of an arch, surrounded the one on each side which 

 marked the crotaphite foramen. In the specimen these are connected by a 

 suture or line, which is regularly convex posteriorly. The superior palpebrae 

 were covered by small separated scales, as are seen among Geccos and Anoles, 

 and were bordered by a larger and continuous series, of about fourteen sub- 



