48 FOSSIL TURTLES OF NORTH AMERICA. 
specimens just mentioned. ‘The number of the specimen is 336. It presents the shell complete, 
the dorsal and the cervical vertebra, the skull quite complete, the shoulder and pelvic girdles, 
and portions of all the limbs. The skull will be described first. 
When buried the skull was undoubtedly complete, but has suffered somewhat during 
disinterment and preparation (plate 5, figs. 3, 4). The bone is extremely brittle and much 
fractured. On this account, and because of the roughness of the surface, the sutures are mostly 
undeterminable. The length from the occipital 
a condyle to the end of the snout is 66 mm., nearly 
Soe i the same as that of Marsh’s specimen. In form it 
3 a is wedge-shaped, but not so narrow as Marsh’s 
laterally crusht specimen. The width at the 
at ro quadrates is 48 mm. The supraoccipital spine is 
% a 4 missing. It is doubtful whether it ever had any 
| considerable length. The parietals lack about 5 
: aan mm. of extending backward as far as the occipital 
; | condyle. The roofing of the temporal region is 
—— =k \ like that of the skull just described. Whether or 
{not the parietals join the squamosals can not be 
wae | determined; they probably do. The orbits had a 
a ei ae diameter of 15 mm., but some allowance must 
ae 1 be made for distortion; they appear to have 
4 as hee f | been larger than those of Marsh’s type. The 
i ~~ /% | interorbital space measures g mm. Apparently 
_ the sutures bounding the frontals laterally can be 
2 distinguisht, and possibly those limiting these 
/ bones anteriorly. Nasal bones can not be distin- 
VE ao ‘(ae guisht. The maxillary bone is only 3 mm. wide 
are fe ae ] below the orbit. The tympanic cavity appears to 
De ee ey have been small. The stapedial passage was open 
aS behind. The quadrates appear to have been 
ae directed slightly forward. The lateral squamosal 
processes extend behind the occipital condyle 
about 5 mm. 
On the upper surface there is observed on 
each side a groove, or sulcus, which starts about 8 
mm. from the midline at the hinder border of the 
temporal roof, runs first forward and inward to 
near the midline, then toward the orbit. Similar 
sulci are seen in Chelydra and it is thus rendered 
probable that the surface of the head was covered 
with horny scutes. 
The basioccipital and the basisphenoid are 
narrow. The suture between the two can not be 
certainly distinguisht. The basisphenoid can be 
traced forward about 30 mm. from the condyle. 
It is 7 mm. wide posteriorly and narrows ante- 
riorly. It is doubtful if the pterygoids came in 
contact at any point. The pterygoid region, where 
narrowest, is 14 mm. wide. Toward the anterior 
end of the basisphenoid there is on each side, 
Fic. 17.—Glyptops plicatulus. Carapace. x4. between this bone and the pterygoid, a foramen, 
No. 336 A. M. N. H. Shows the various such as is seen in Baéna, probably for the passage 
bones and many of the scutes. of a vein. In the skull here described a groove 
Fic. 18.—Glyptops plicatulus. Carapace. 4. proceeds backward for some distance, and the 
No. 1357 Yale University. Shows only the appearance is such that the presence of a slit 
bones. Figure from U.S. G. S. between the bones is suspected. The ectoptery- 
