324 FOSSIL TURTLES OF NORTH AMERICA. 
The gular scutes are 41 mm. long; the humerals, 25 mm.; the pectorals, 55 mm.; the 
abdominals, 70 mm.; and the femorals, 47 mm. 
The axillary scute extends backward in a long point to come into bare contact with the 
fifth marginal. The inguinal scute extends forward and joins narrowly the sixth marginal. 
This species differs from E. naomi 
in the form of the vertebral scutes, in 
the lack of grooves for the sulci of the 
carapace, in the very different form of 
the front of the anterior lobe, and in 
the axillary and inguinal scutes. The 
\ broad neurals, the very broad fifth ver- 
tebral scute, and the plastral lip differ- 
entiate it from £. stevensoniana. The 
\ acute anterior border of the carapace, 
© the plastral lip, and the advanct posi- 
a tion of the humero-pectoral sulcus sep- 
. arate it from E. shaughnessiana. The 
very different plastral lip, among other 
characters, removes it from E. septarza. 
E. ocyrrhoé has the costal plates dif- 
ferentiated so that the ends are alter- 
nately wider and narrower; the epi- 
plastral lip is different from that of E. 
arethusa; as are also the axillary and 
inguinal scutes. £. egle has the verte- 
Fics. 421 AND 422.—Echmatemys arethusa. Anterior bral scutes urn-shaped, the anterior 
lobe of plastron. x3. No. 5920 A. M.N.H. lobe is very different, and the axillary 
and inguinal scutes fall short respect- 
ively of the fifth and sixth marginals. 
The plastral lip of E. cyane is widely different; the axillary scute falls short of the fifth 
marginal; the inguinal far short of the sixth; the second and third peripherals measure 
together 64 mm. along the free border, while the same bones in the type of E. arethusa measure 
85mm. E£. haydent, so far as known, differs in having the fourth neural octagonal, the verte- 
bral scutes narrower, and a very different form of epiplastral lip. 
421. Lower surface. 422. Upper surface. 
Echmatemys cyane sp. nov. 
Figs. 423-427. 
No. 5924 of the American Museum of Natural History is a fragmentary specimen present- 
ing most of the left side of the carapace, including four neurals, most of the left side of the 
plastron, and a part of the right side. The specimen was secured by the expedition in 1903, 
into the Bridger Eocene, at Grizzly Buttes, Wyoming. Its horizon is therefore that called B. 
The length of the carapace (fg. 423) of this individual can not be exactly determined. 
From the front of the nuchal to the hinder end of the sixth neural is 246 mm., from which fact 
- it is estimated that the carapace had a length of 340 mm. Like 
Pa a eee | write most of the Bridger species of the genus, this species had a thick 
: shell. The surface of the carapace is mostly smooth. 
Of the nuchal only a portion of the left side is present, but 
; a this shows that its width in front was very close to 50 mm. The 
; 33-5 30 greatest thickness is 15 mm. The first neural is not present. 
5 29 30 Those preserved show the dimensions given in the table here- 
6 22 30 
with. These neurals have a thickness of 12 mm. The costals 
have the two ends of each about the same width. The width of 
the first costal equals 77 per cent. of its height. 
The dimensions of some peripherals and of some vertebral and marginal scutes are given 
in the table on the following page. The third peripheral is half as high as the first costal. 
