162 FOSSIL TURTLES OF NORTH AMERICA. 
Dr. W. B. Clark has referred provisionally (Johns Hopkins Uniy. Cire., xv, 1895, No. 45 
Bull. U.S. Geol. Surv., 141, p. 59) some fragments of a large turtle to Euclastes. One of these 
fragments has been again mentioned and figured by Dr. Case in the Eocene volume of the 
Geological Survey of Maryland ( p. 97, plate x, fig. 7). The fragment is not susceptible of 
generic determination. 
Rhetechelys platyops (Cope). 
Plate 29, figs. 2, 3. 
Euclastes platyops, Corr, Proc. Acad. Nat. Sci. Phila. 1867, p. 41; Cook’s Geol. New Jersey, 1868 
(1869), p- 7353 heer Naturalist, 11, 1869, p. 89; Ext. Batrach., Reptilia, Aves N. A., 1869, p. 
149, plates vi, vii, fig. g; Vert. Cret. Form. West, re p- 259. 
Lytoloma paapee Hay, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 442.—W1kELAND, Amer. Jour. Sci. 
(4), XvilI, 1904, p. 185. 
?Propleura sopita, CoPE, Ext. Batrach., Reptilia, Aves N. A., 1869, p. 140 (Harrisonville specimen). 
All that we know at present regarding this species is what is to be derived trom the type 
skull. This is in the collection of fhe Academy of Natural Sciences at Philadelphia. It was 
found in a coarse granular limestone, at Hurffsville, Camden County, New Jersey. This 
deposit belongs to ie Upper Cretaceous and was regarded by Cope as equivalent to the Fox 
Hills group. The species formed the type of Cope’s genus Euclastes, a preoccupied name. 
The oo was a large one, the total length being estimated by ‘Cope as II inches, about 
280 mm.; but this must have included the supraoccipital process. At any rate, the length was 
equal to that of the largest specimens of Caretta. The occipital condy le is missing, sett the 
length from the premaxillae to this condyle must have been close to 200 mm., perhaps a little 
more. The width, a short distance behind the orbits, is 220 mm. From this widest part the 
aiteral outlines converge rapidly to the pointed snout. Beneath the orbit the outlines are 
slightly concave. The “angle included between the borders of the maxilla is somewhat less 
than a right angle. The roof is broad and deprest, the frontal region being flat. The slope 
from the rear to the nasal opening is only slightly sinuous. There is no such sudden descent 
from the orbits to the premaxilla as We see in the species of Glossochelys. The temporal region 
was broadly rooft over, as in Caretta, but extended backward still further. The various bones 
appear to have been disposed about as in the living genus mentioned. 
The orbits look outward, forward, and upward. The upward inclination exceeds that of 
Caretta. The greatest diameter of the orbit is 63 mm. The least interorbital width is about 
5omm. The frontal bones are more produced forward than in Caretta, their suture measuring 
55mm. They are excluded from the rim of the orbits by the union of the postfrontals with she 
prefrontals. The latter bones meet along the midline a distance of 12 mm. 
The nasal opening has a width of 30 mm. It looks forward and strongly upward. As in 
other Cryptodira, the prefrontals send dow nward on each side a column of hone to the vomer. 
The roof of the mouth resembles in general that of Caretta, but there are important differ- 
ences. The cutting-edges of the cacclles are only feebly developt, descending but little below 
the level of the grinding surface. This surface is formed by the union of the palatal plates of 
the premaxillz, ivan. vomer, and palatines. It extends backward a distance of nearly 
100 mm. from the premaxilla. It is somewhat concave on each side of the vomer and in the 
premaxillary region. In the roof of the mouth the maxilla are each 41 mm. wide; the palatines 
about 26mm. The vomer is 50 mm. long and 28 mm. wide. 
The occipital condyle is missing, bar the choane fall within the anterior half of the length 
to the roof of the mouth. They are bounded laterally by the palatines and anteriorly by dhe 
vomer, the edge of this being g8 mm. behind the tip of the snout. They are thus quite different 
from those of the species of Erguelinnesia. The palatal openings of the temporal fossa are 
broader than long. The borders of the pterygoids were strongly emarginated. 
Between the anterior ends of the premaxillz is a perforation supposed to be for the recep- 
tion of a hook on the lower jaw, as in Macrochelys. 
Professor Cope supposed that the whole length of the animal which possest this skull 
was a little over 6} feet; but it is not safe to estimate the size of a turtle from the size of the 
head. Nevertheless, it must have been a large and formidable brute. Probably it haunted 
the coasts of the Cretaceous seas, betaking itself at times to some distance from the shore. 
