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1877. ] 83 [Cope. 
dermal suture. At its iateral extremities instead of continuing to the mar- 
ginal scuta as in Emydoid genera, it turns forward and terminates at the 
inguinal notch, as in genera with intermarginal plates, as Adocus and Der 
matemys. But the sutures of the intermarginals in the specimen are, if 
they ever existed, very obscure, owing to exposure to the weather. Never- 
theless there is sufficient indication of them on one side, to render it toler- 
ably safe to infer their existence. Anterior to the abdomino-pectoral 
suture, the border of the plastron is crossed by emarginations representing 
three scutal sutures, defining the humeral, gular, and intergular scuta. 
The courses of these sutures across the plastren are obscure. The humero- 
pectoral suture commences on the margin just in front of the axilla and ex- 
tends forwards parallel with the border, becoming a deep open groove, 
whichis apparent on both sides of the plastron. It then turns backwards, and 
appears to cross the plastron behind the mesosternum, presenting a concav- 
ity forwards. The next suture in front appears to cross near the middle of 
the mesosternal bone, presenting a strong concavity forwards. ‘The rela- 
tion between the intergulars and the gulars is difficult to discover. The 
suture between them at the free margin is distinct, but after proceeding in- 
wards a short distance it appears to divide and take two directions. One 
depressed line extends backwards to the humero-gular suture, cutting off 
triangular gulars and extending the intergulars back to the humerals as in 
Adocus. The other depression extends directly across the anterior lobe, 
cutting off small intergulars as in Baéna. In either case the arrangement 
represents a genus distinct from either of those named, If the intergulars 
extend to the humerals they are double, the mesosternal region being di- 
vided by a distinct longitudinal dermal suture. If the intergulars are 
short, with the gulars in contact behind them, the arrangement is equally 
distinct from Adocus. From Baéna the absence of intersternal bones, and 
the Emydoid mesosternum distinguish it. It approaches also Polythoraa,* 
and may indeed belong to that genus. But it does not appear that the hu- 
merals and interhumerals are distinct in the Georgia turtle, and no inter- 
marginals are observed in Polythorax. It is therefore necessary to give the 
present genus a name to be used until its relations to the latter are posi- 
tively ascertained. I propose AMPHIEMYs for the genus, and A. OXYSTERN- 
UM as the specific name. 
Specific characters. The plastron is nearly plane in the transverse direc- 
tion ; longitudinally the posterior lobe is a little raised above the plane, 
and the anterior lobe rather more so. 
The general form is elevated, the vertical diameter being large when 
compared with the longitudinal and transverse, which preserve usual pro- 
portions. The border of the carapace is not flared at the sides, and rises 
anteriorly to the nuchal bone. The free anterior margin is somewhat un- 
dulate. The anterior half of the carapace does not display any median or 
lateral keels. 
The nuchal bone is considerably wider than long, and the costal and 
* Cope, Proceed. Acad. Philada, 1876. Nov. 
