FOSSIL TURTLES OF NORTH AMERICA. 
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Genus GRAPTEMYS Agassiz. 
Shell moderately elevated, with dorsal keel more or less strongly developt. Neural plates 
hexagonal, with broad ends in front. Hinder border of carapace serrated. Inguinal buttresses 
rather feeble, articulated to the fifth costals. Humero-pectoral sulcus crossing behind the 
entoplastron. Plastron with a median notch behind. Alveolar surfaces of the upper and the 
lower jaws broad, flat, and smooth. Alveolar plate of the vomer in contact with the palatines. 
Choanz between the hinder borders of the orbits. Symphysis of lower jaw long, equal to 
half of the distance between the quadrates. 
The ope of this genus is G. geographic a, the geographic terrapin of the Mississippi 
Valley (figs. 1, 2, shell). This genus is distinguisht from Chrysemys, Pseudemys, and Trach- 
emys by its ae, and dentary alveolar surfaces, which are broad, flat, and without longitu- 
dinal ridges. From Malaclemys it differs in having broader alveolar surfaces, and especially 
in having the yvomer in contact with the palatines on the alveolar surfaces. This articulation 
and the broad: flat crushing-surfaces of the jaws remind us strongly of the condition found in 
Lytoloma, as well as in the Toxochelyidz and the Cheloniide; and show us that similar 
structures may arise independently in different groups. The evident purpose of these broad 
jaws in Graptemys is the crushing of hard food substances. G. geographica lives habitually 
on mollusks. The relations of the palatines and the vomer need further study. 
aes can be little doubt that Graptemys has been derived from Malaclemys 
Von Reinach described (Abhandl. Senckenb. Gesellsch., xxvitt, 1900, p- 92, "plate XXX 
fig. 1) a new genus and species (Promalococlemmys boule ngert) believed to be closely related 
to Malaclemys. here can be hardly a doubt that what is represented 1 in his figure as the 
hinder end of the plastron is in reality the anterior end of another specimen. 
Graptemys? inornata (Loomis). 
Figs. 455, 456. 
Chrysemys inornata, Loomis, Amer. Jour. Sci. (4), XVIII, 1904, p. 429, fig 18 
This species is based on a nearly complete shell which was discovered i Dr. F. B. Loomis 
in the year 1903, in the Titanotherium beds of the White River deposits, in Spring Draw 
Basin, 10 miles east of Creston, Meade County, South Dakota. The specimen lay beneath 
the skull of a titanothere; but, as no other skeletal parts of the turtle were found, the shell 
had probably drifted thither. Through the liberality of Dr. Loomis I have been enabled to 
study the specimen. 
In outline the shell is broadly oval, broadly rounded in front, and rather pointed behind, 
The elevation of the shell in life can not be determined, it having been crusht flat during 
burial. The length of the carapace (fg. 455) is 303 mm.; 
the greatest Sie 253 mm. Its margin is slightly excavated 
ae ene ees in front: with shallow notches at me outer onde of the pos- 
ee terior marginal sulci, and with a notch in the border of the 
Neural 1..... 27 22 pygal. There appears to have been a rounded carina on the 
sae - a i front of the carapace, and this reappears near the rear. 
Neural 7 26 23 The nuchal bone has a length of 53 mm. and a width 
Neural 5 2 20 of 66 mm. The eighth neural 1s followed by 2 suprapygals. 
ee _ The accompanying table presents the dimensions of the 
Neural 8 9 18 median bones behind the nuchal. 
on z 25 = The borders of the carapace in front of and behind the 
Pypal..... a 31 bridges are acute and the bones are thin. The second per- 
ipheral bone has a width of 38 mm. at right angles to the 
margin of the shell; the ninth, a width of 40 mm. The sulci 
between the marginal and the costal scutes run along on the peripheral bones a short distance 
below the costo- peripheral sutures, except in front, where they deviate further from the sutures. 
Posteriorly the sulcus crosses the midline on the rear of the second suprapygal. The nuchal 
scute is 14 mm. long and 15 mm. wide. 
The vertebral scutes are narrow. Each of the anterior four is about 50 mm. wide. The 
fifth has an extreme width of 70 mm. 
