EMYDID. 
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Echmatemys naomi sp. nov. 
Plate 51, figs. 1, 2; text-figs. 442-444. 
The type of the present species is a finely preserved shell which was collected by the 
American Museum expedition of 1903, in the Bridger beds of Wyoming. The locality is 
Little Dry Creek, near the western part of Grizzly Buttes and the level is the lower part of 
horizon B. The shell has suffered shght downward crushing, 
but none of the characters have thereby been obscured. The 
Element. Length. Width. “ - ; 
number of the specimen 1s 5975. 
Mek The total length of the carapace (plate 51, fig. 1; text-hg. 
Uchal eee, 55 70 pe Es ose 5 Ae 
aa ey saa 28 442) 1s 360 mm. The width taken across the middle is 263 
Neural 2...... B 33 mm., and this is the greatest width. The front of the shell is 
Neural 3....-. 33 33 in no way contracted. The hindermost peripherals appear to 
Neural 4...... 32 3 have, b % fohely h " Th bl sn | 
Neutalese cts a 31 ave been slightly notcht at the sutures. e table gives the 
Neural 6...... 26 2 dimensions of the central row of bones. 
eas : otc a i The width of the free border of the nuchal is 42 mm. ‘The 
Suprapygal 1... 31 34 costals present little that is novel. The proximal ends are 
Som ADEs 2..| 37 7° usually of nearly the same width as their distal ends, except that 
DY Gall cerercvera! aus 31 39 i % 
: the last three have their distal ends expanded somewhat. 
The table below presents the dimensions of some of the 
peripherals. The height of the third peripheral is 53 per cent. of the hinder border of the 
first costal. 
The nuchal and the first pair of peripherals have an acute free border. The greatest thick- 
ness of the first is 19 mm. The free border of the second is subacute and passes into the 
rounded free border of the third. 
Dimensions of peripherals. Dimensions of marginal scutes. Dimensions of vertebrals. 
Width = Width ; Length “| Width at /, 
No. | Height. of free of costal No Detent: Poccateat at free No. Length. anterio reece 
a igi: “in front. height. | eee Was rs n10r width. 
border. border. Z ; border. ___end. 
I 42 34 14 1 20 25 33 I 63 81 81 
2 42 35 20 2 24 28 32 2 70 42 74 
3 43 42 27 3 22 3 38 3 7° 8 7° 
6 46 48 B 4 22 28 45 4 68 48 71 
8 52 3 32 9 36 38 40 5 61 32 79 
The posterior peripherals are flared moderately upward. They are rather thin and pass 
out into a sharp, thin, free border. The thickness of the ninth at the longitudinal sulcus is 
g mm. 
The first costal is four-fifths as wide, fore and aft, as it is long on the hinder border. 
The upper surface of the shell is very uneven. Large parts of the sulci run in very deep 
grooves. Between them the surface is usually rough and pitted. There is no keel. In the 
middle of the nuchal there is a slight, broad, rounded, longitudinal elevation and a similar one 
on the suprapygals and pygal. The sulcus running around the carapace on the nuchal, the 
peripherals, and the second suprapygal, lies in a deep groove. This groove has so weakened 
the peripherals in its course that the pressure has caused them to yield along this sulcus. The 
sulci between costals 1 and 2 and between 2 and 3 lie in very deep grooves, especially at their 
upper ends. The hinder ends of the sulci bounding laterally the three anterior vertebral scutes 
lie in deep and broad grooves. The sulci between many of the marginal scutes occupy 
deep grooves. 
The nuchal has a length of 1g mm. and a width of 15 mm. 
The dimensions of marginal scutes are shown in the table above. 
The costo-marginal sulci run far below the costo-peripheral sutures. 
The vertebral scutes are broad and rather strongly urn-shaped; their dimensions are pre- 
sented in the table above. 
The plastron (plate 51, fig. 2; text-fig. 443) has a total length of 326 mm. The front 
extends somewhat beyond the border of the carapace. The length of the anterior lobe is 96 
