DERMATEMYDID&. 277 
No. 6110 has been a slightly smaller individual. Fig. 348 represents the front lobe of the 
plastron. It is somewhat more pointed in front than that of the type. What is most interesting 
is the presence of portions of the gulo-humeral sulci. The extent and positionof these are shown 
in the figure. The presence of these indicates that there has occurred in this genus a coales- 
cence of the gulars and the humerals. 
Fig. 349 represents the right humerus seen from the dorsal surface. The general form is 
that of the humerus of Chelydra. 
Baptemys fluviatilis sp. nov. 
Plate 42, figs. 1, 2; text-figs. 350, 351. 
This species is based on a chelonite which was presented to the American Museum of 
Natural History by Mr. Sidney Dillon, of New York City, in 1879. It is said to have been 
obtained by him in Colorado, but there is no record of the exact locality, nor of the formation 
a 
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Fics. 250 AND 261.—Baptemys fluviatilis. Carapace and plastron of type. 4. 
3 35 pd P P YE 4 
350. Carapace. Restored costal and vertebral scutes indicated by interrupted dotted bands. 351. Plastron. 
from which it was derived. The specimen probably belongs to the Bridger formation and 
there may be some error regarding the region. 
The specimen consists of a mass of gray sandstone, broken into two pieces, which bears 
considerable portions of the carapace and impressions of other portions and a fragment of the 
plastron, together with an impression of the inner surface of practically the w hole plastron. 
While we must regret the absence of many parts which might evidently have been preserved, 
there is enough of ae shell present to furnish us with the eeecntials of the structure. 
This shell has a length of 438 mm. and a width of 312 mm. The carapace (plate 42, fig. 
text-fig. 350) forms a high vault which rises from the lower surface of the plastron een 
