THALASSEMYDID&. S55 
(Geol. Surv. Maryland, Eocene, 1901, p. 97. pl. x, hg. 7) has repeated Dr. Clark’s words and 
figured one fragment. The materials are generically indeterminable. 
Lytoloma angusta Cope. 
Plate 28, figs. 5, 6; text-figs. 191, 192. 
Chelone sopita (in part), Leipy, Smithson. Contrib. to Knowledge, x1v, 1865, p. 105, plate xix, fig. 
Lytoloma angusta, Cope, heten Naturalist, m1, 1869, p. 105 (nom. nud); Ext. Batrach., Reptilia, reer 
N. A., 1869, p. 145, plate xi, figs. 1, 1b; Vert. Cret, Form. West, 1875, p. 257 —Hay, Bibliog. and 
Cat bse Vert. N. A., 1902, p. 442. 
Cope’s first mention of this species was in the American Naturalist, as quoted above, but 
this mention was made only incidentally and what was said is not sufficient to distinguish 
either the species or the genus from various other turtles. When he came to describe and figure 
the species Cope stated that his materials consisted of three peripheral bones, a fragment of a 
costal,and a lower jaw. He says that the costals and marginals were found at the same time and 
place as the jaw and probably belong to it. It seems that he regarded the peripherals as the 
type of the species, and since he figures only one of these, this especially must be taken as the 
type. That he so regarded the peripherals is evident from the fact that 
from peripherals alone of this species and L. jeanes: he drew all his generic 
characters. Further proof is afforded by the specimen of the jaw itself, 
which bears, in Cope’ s writing, the label “?Lytoloma angusta Cope, Bir- 
mingham, N. J.” Incase he fod lookt upon the jaw as the type he could 
hardly have questioned its belonging to the species. It is wholly prob- 
able that at least the figured peripheral and the costal belong with the 
jaw; and until it has been shown that they do not, all may pass as types. 
These specimens were obtained in the upper greensand beds of the Creta- 
ceous, at Birmingham, near Pemberton, New Jersey. Inasmuch as the jaw 
is labeled by Cope as coming from Birmingham, itis probable that the 
specimens were obtained from some marl-pit between the two towns. 
They are now in the American Museum of Natural History and bear the 
number 1133. 
The figured peripheral (plate 28, fig. 6) is said by Cope to belong to 
the left side, but on the bone itself he has written “5 R,” from which 
it appears that he regarded it as the fifth of the right side, and such it 
——~s.---' seems to be. It has a length, along the acute free margin, of 67mm. A 
section of the bone is triangular, and therefore it shows three faces (fg. 
ilmenite. 191). The visceral face is 22 mm. wide, somewhat concave, and contains 
Peripherals of in the hinder half of the bone a deep conical pit for the rib-end of the 
type. x3. third costal. “The upper face is slightly concave at right angles with the 
free border, 22 mm. wide at the anterior end, 29 mm. at the posterior. 
1g. Section through filth The inferior face is slightly convex and 32 mm. wide at each end. 
peripheral. Pit R ere ee! re os 
shown by inter- Another peripheral (fig. 192) is markt by Cope “?2 R.” It has a 
tupted line. length of 70 mm., a thickness at the visceral face of 16 mm. at one end 
eee ie eae ae and 13 mm. at the other. The upper and lower faces are somewhat con- 
Bee Pept vex. In the free border there is a broad emargination. At the bottom 
of this emargination the bone is 28 mm. wide. At one sutural end the width is 34 mm. There 
is no rib-pit in the visceral face. The peripheral, supposed by Cope to be the fourth, is not 
now with the other bones. 
The fragment of costal has a width of 47 mm. near the sutural border for the neural. At 
the middle of the width the thickness is 10 mm.; at the sutural border it is about 4 mm. As 
stated by Cope, there is present the sulcus bounding one of the vertebral scutes. From a 
comparison with the figure publisht by Wieland, and ‘here reproduced (fig. 196), this costal is 
believed to be the endl. of the right side. The outer angle of the vertebral scute is placed neat 
the hinder sutural border of the bones, at a distance of 50 mm. from the neural. 
The lower jaw (plate 28, fig. 5) is of the greatest interest. It is considerably eroded and 
does not lend itself well to illustration. It is remarkable for the great length of the symphysis, 
Fics. 191 AND 192.— 
