4 FOSSIL TURTLES OF NORTH AMERICA. 
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This species is stated to be based on portions of 3 individuals, which were collected for 
Professor Cope by Mr. G. W. Marnock, in southwestern Texas. The beds are stated to 
belong to the Pliocene; but now they are regarded as Pleistocene. 
In the collection of the Philadelphia Academy there 1s found a part of the anterior half of 
a carapace which evidently belongs to this species i and which is probably one of the three por- 
tions referred to by Cope in his description. It is labeled in Cope’ s handwriting, and is stated 
to have been collected by G .W. Marnock, from the Pliocene beds of Atascosa County, Texas. 
Terr ‘a pene marnoc hit was described by Cope on the page following the description of the present 
species and was said to come from the same formation. Rion the American Naturalist, 
vol. x11, 1889, page 161, we learn that the latter-named species was found in the Equus beds. 
From these Equus beds we have therefore T estudo atascose Hay, Terrapene marnochi (Cope), 
Trachemys bisornata (Cope) ) and T. trulla Hay. 
The specimen (plate 56, fig.1) in the Philadelphia Academy consists of the nuchal, the first 
right peripheral, the first and second right costals, parts of the third and fourth right costals, 
the first, second, fourth, and fifth peer! and the proximal portions of the first a second 
left costals. The third neural is missing, but its dimensions and form are easily determined. 
The nuchal resembles that of 7. scripta. In front it is thin-edged and sharp. It is slightly 
notcht at the ends of the sulci bounding the nuchal scute, and between the ends of these sulci 
are 3 teeth. Its length along the madline 4 is 4g mm.; its width anteriorly, 34 mm.; the max- 
imum width, 55 mm. ‘The table herewith gives the dimensions of the neurals represented. 
The thickness of the fourth neural is 7.5 mm. The first is 
oval. The second is broadest in front ae deeply excavated to 
receive the frst. The other neurals are hexagonal, with the broad 
end in front. 
Neural. Length. Width. 
: oe ah The second costal is 26 mm. wide near its neural; the third 
3 25 23 is 28 mm. wide; the fourth, 23 mm. They are rather thick proxi- 
4 21 24 mally, as is indicated by the thickness of the fourth neural. 
5 22 22 
The nuchal scute is 19 mm. long and 10 mm. wide posteriorly. 
The first vertebral is 46 mm. long, 33 mm. wide in front, 40 mm. 
behind. The second is 52 mm. long and 50 mm. wide. The third is 43 mm. long, 54 mm. 
wide. The sulci are deeply imprest. 
Along the midline there appears a broad and shallow groove, beginning with the first 
neural, showing most conspicuously on the second, and persisting on the fourth and fifth. 
There is only a suggestion of a median carina. 
The ornamentation of the carapace has been described by Cope, and his description 
applies to the specimen here considered. The whole surface of the carapace, as far as known, 
is sculptured into ridges and grooves. The areas occupied by the vertebral scutes are smoothest, 
but here too we find some sculpture, On those costal bones which are traverst by the inter- 
costal sulci we find that the area in front of the sulcus presents sharp ridges, some of which 
run at right angles with the sulcus, while others cross these parallel with the sulcus. Behind 
the Sulets the ridges run only at right angles with the sulcus, and these ridges are broader than 
those in front of the sulcus. Those euerile which are not traverst by the intercostal sulci are 
ornamented more like the anterior portion of the costal plates first described. The ornamenta- 
tion may be otherwise described as follows: Along the front of each scutal area there is a band 
of broad ridges. Most of the remainder of the area is occupied by ridges and grooves running 
parallel with the length of the animal and crost by a system of less conspicuous ridges. The 
lower border of the costal scutal area, that formed by the upper borders of the peripheral bones, 
is occupied by coarse ridges at right angles with the length of the animal. 
The sculpture of the « carapace of this tortoise has been compared by Cope to that found on 
T. elegans. It appears to be still more like that of a large specimen of 7. scripta now in the 
American Museum of Natural History. It can hardly ‘be doubted that the fossil species 1S 
closely related to, perhaps the immediate ancestor of, both T. ele gans and T. scripta. It has 
differed from T. ele gans in having a considerably thicker and more boldly sculptured carapace; 
from T. scripta apparently i in having a less well-defined dorsal carina. Remarks on the pos- 
sible identity of this species with ve mys petroler will be found on page 353. 
