280 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



CATOPTERUS GRACILIS Redfield. 



Plate 12, figs. 1, 2; plate 13, figs. 1, 2. 



Catoptei-us gracilis J. H. Redfield, Ann. Lyceum Nat. Hist., N. Y., vol. 4, 1837, 

 p. 37, pi. 1. — Newberry, Monograph. U. S. Geol. Surv., vol. 14, 1888. p. 55, 

 pi. 16, figs. 1-3.— Eastman, Conn. State Geol. Nat. Hist. Surv. Bull. 18, 1911. 



Among the most instructive specimens that have come under the 

 ^Titer's observation for elucidating the much vexed subject of the 

 cranial osteology of this species and genus, first mention should be 

 made of one of the original cotypes of C. gracilis, now preserved in the 

 Peabody Museum at Yale University ; and scarcely inferior in impor- 

 tance are several small specimens from the Connecticut Valley region 

 belonging to the United States National Museum. Two of these lat- 

 ter, from Durham, Connecticut, are shown in the accompanying plate 

 12, and a larger one from Guilford, in plate 13, figm-e 1. The original 

 of plate 13, figure 2, from the Trias of Dm-ham, Connecticut, is of 

 value for illustrating how the depth of body is apparently increased 

 by accidental crusliing prior to fossihzation. In this specimen it is 

 easy to distinguish the row of dorsal ridge-scales which has been 

 pushed over to one side and occupies a position at some distance 

 below the upper contour hne of the fossil. Examples of mechanical 

 deformation of this kind point to the extreme degree of caution that 

 is necessary in attemj^ting to trace the dorsal and ventral contours of 

 crushed specimens of this and the accompanying genus Semionotus 

 in the Triassic rocks of North America. 



To speak more particularly of the cranial osteology, it must be 

 admitted that scarcely anything can be added to the facts already 

 known. The bones forming the cranial roof are as a rule fu-mly coal- 

 esced and their sutm-es concealed by the tubercular ornamentation. 

 Apparently the superior border of the orbits is formed by the large- 

 sized frontals, which are bounded behind by the parietals (the latter 

 separated in the median Hne by a small-sized supra-occipital) and 

 squamosal. The inferior border of the orbit is formed by the expanded 

 posterior portion of the maxilla, which is of relatively large size and 

 decidedly Palaeoniscid-like in form. This plate bears numerous fine, 

 acutely conical teeth, and there is also present a small dentigerous 

 premaxilla, which is often found detached from the other mouth- 

 parts. 



Just how the facial plates are arranged in the space lying between 

 the orbit and shoidder-rcgion (clavicle) is difficult to determine. 

 Newberry's interpretation of the elements covering this area in a 

 single specimen studied by him is open to serious question. At least 

 one postorbital is present in its normal position beliind the eye, and 

 there may possibly be another, or suborbital, below it. Behind these 

 plates is the area commonly occup'iod by the operculum and suboper- 



