262 FOSSIL TURTLES OF NORTH AMERICA. 
agonal, with the broader end forward; the third being 56 mm. long and 25 mm. wide; the 
fourth, 46 mm. long and 22 mm. wide; the fifth, 38 mm. long and 22 mm. wide. The sixth is 
hexagonal, 20 mm. long and 28 mm. wide. The seventh neural is pentagonal, 22 mm. long and 
17 mm. wide. It has the appearance of having been crowded far forward out of its place. 
There is a single broad suprapygal whose length is 46 mm. and width too mm. 
The members of the sixth, seventh, endl eighth pairs of costals respectively meet along 
the midline. The suture between those of the eighth pair is 82 mm. long. The peripherals 
are unusually high, about 100 mm. along the Rides somewhat less coward each extremity of 
the animal, the frst and eleventh being Bnet 64 mm. high. The free peripherals are thin at 
the borders, and the hinder ones are seduced to a sharp edge. The thickness of the second 
peripheral, near the upper border, is 20 mm.; that of the ninth, at the upper border, is 16 
mm. There are 11 of these peripherals on each side. 
As stated, it is dificult, in a few cases impossible, to determine satisfactorily the bound- 
aries of the epidermal scutes. In front there is a very narrow nuchal, about 10 mm. wide 
and 20 mm. long. This is followed by a first marginal, 58 mm. along the front edge and 
30 mm. fore and aft. The sulci between the marginals and the costal scutes appear to run at 
a considerable distance below the sutures between the costal and peripheral bones, the mar- 
ginals being about 75 mm. high. The limits of the vertebral scutes are satisfactorily deter- 
mined, except those of the fifth. The first vertebral is 80 mm. long and 130 mm. across its 
anterior end. The second is 100 mm. long and 65 mm. wide; the third go mm. long and 66 mm. 
wide; the fourth apparently 108 mm. long and close to 58 mm. wide. The fifth was probably 
115 mm. long and about 130 mm. wide. 
The surface of the carapace, including the lower faces of the peripherals, is ornamented 
with narrow and low longitudinal wrinkles of which there are from five to eight in a 10 mm. 
line. They are possibly “due to the great age of the specimen and may be wanting in the 
younger individuals. 
The plastron (plate 39, fig. 2; text-fig. 324) is well developt, altho it leaves wide spaces 
between it and the carapace. It was apparently quite flat, altho now somewhat concave 
transversely, the result possibly of pressure. The total length is 415 mm. The anterior lobe 
projects nearly as far forward as the anterior border of the carapace; but the hinder fails to 
extend as far backward as the carapace by about 115 mm. The anterior end of the plastron 
is very slightly emarginated; the posterior end is broadly rounded and without notch. 
The length of the anterior lobe is 100 mm.; its width at the axillary notch 209 mm. It 
decreases in widen gradually at first, then rounds rapidly to the notch in front. Its thickness 
near the frontisg mm. The length of the posterior lobe is 132 mm.; its width at the inguinal 
notches is 1g0 mm. The bridge i is 180 mm. in width. The axillary and inguinal batieeees 
do not appear to extend inward beyond the adjacent borders of the plastron. 
The entoplastral bone is short and broad and with a nearly straight hinder border. Its 
length is 55 mm; its width,go mm. The hyoplastral bones meet along the midline for a dis- 
tance of 100 mm. The suture separating the hypoplastrals from the xiphiplastrals is believed 
to be placed as shown in the figures. The former bones occupy 135 mm. of the midline; the 
latter, 84 mm. 
Gular and intergular scutes seem to be present and to have the positions and forms given 
them in the figures. The intergular area is evidently divided by a median sulcus. The two 
taken together are 75 mm. wide and 50 mm. long. The gulars are small, triangular, and 
widely separated by the intergulars. 
The humero-pectoral sulcus crosses the midline at the hinder end of the entoplastron. 
The humerals meet on the entoplastron for a distance of 48 mm. The pectorals extend 
along the midline only 46 mm. Altho the femoro-abdominal sulcus is not as distinct as 
might be desired, it is probably placed correctly in the figures. The abdominals thus have a 
ee and-aft extent of 128 mm. The femorals extend along the midline 80 mm.; the anals, 
67 mm. 
On the bridges of the plastron there are at least four inframarginals. Of these, the one 
in front is small and square; the second, pentagonal; while the fifth is probably hexagonal. 
The third is 95 mm. long and 42 mm. wide, and may possibly be subdivided; but no sulcus 
is visible. 
