302 FOSSIL TURTLES OF NORTH AMERICA. 
Professor Cope tells us that this species was based on fragmentary specimens of 5 or 6 
individuals. Portions of these are now in the American Museum of Natural History, but the 
bones figured by Cope are in the U. S. National Museum at Washington, and have the catalog 
number 4061. The types and other specimens obtained by Cope were collected in the 
Green River beds of the Wasatch formation, at Black Buttes, Wyoming, in 1872. A note in 
Professor Cope’s handwriting, accompanying some specimens at Washington, states that they 
were found in the first lignite beds of the Eocene at Black Buttes. 
As stated by Cope, the markt peculiarity of the present species was the broad and abruptly 
sunken sulci which separated the epidermal scutes. There was a dorsal carina and this was 
conspicuously intersected by the sulci which crost it. The neurals are relatively broad. Cope 
gives the length of one as 17 mm. and the width as 18 mm. A neural in the American 
Museum, No. 1120, is 19 mm. long and 23 mm. wide at the broader end; its thickness at the 
border for the costal is 5 mm. Sometimes the carina is broader in front of the sulcus which 
crosses it and sometimes narrower. Sometimes (Cope’s figure 32) the sulci are shallow. 
The neural which furnisht the figure just referred to has a thickness of 5.5 mm.; while 
the others figured are only about 4 mm. thick at the borders. Cope’s fig. 28 does not repre- 
sent a neural, but probably the hinder suprapygal. If so, the hinder marginal scutes extended 
upon it. The figure is inverted. Fig. 14, plate 45, is taken from No. 1184 of the American 
Museum. It is either the third or fifth neural. 
The peripherals are rather thin, and they flare somewhat upward toward the tree border. 
One figured by Cope (his plate xviii, fig. 29) had a width of 16 mm., a height of 23 mm., and 
380. 381. 382. 
Fics. 380-383.—Echmatemys megaulax. Peripherals and entoplastron. 1. 
o. Section across posterior peripheral. No. 1184 A.M.N.H. 
1. Right third or left seventh peripheral. No. 1184 A.M.N.H. 
2. Section of peripheral of fig. 381. 
3- Entoplastron of type of Emys pachylomus Cope. Specimen in A.M.N.H. 
a thickness of 5 mm. It appears to be either the eighth or the tenth of the right side. In the 
upper border is a pit fora rib. This, like others belonging to Cope’s specimens, had the sulci 
deeply imprest. Cope’s fig. 31 1s almost certainly the Fipst right peripheral and is quite dif- 
ferent from the corresponding bone of £. euthneta, being 5.2 mm. thick where it joined the 
nuchal, while that of £. euthneta is g mm. thick. Cope’s fig. 30 appears to be that of the 
second right peripheral, altho it does not join the first accurately. Fig. 15 of plate 45 is from 
a peripheral of lot No. 1184. Its breadth at the free border is 19 mm.,; its height, 20 mm.; its 
thickness, 5 mm. At the free border the edge is rather abruptly turned upward. Another 
(text-fig. 380, section) is greatly thickened below the costo-marginal sulcus. Both of these are 
posterior peripherals. Text-figs. 381, 382 represent the right third or the left seventh periph- 
eral. Its width is 17 mm.; its height, 19 mm.; the thickness of the anterior sutural border, 
7mm. On the inner face is a rough groove for the buttress. If this is the third peripheral it 
presents in its acute free border a great contrast to that of E. testudinea. The sulci are not 
broad and deep as they are in other posterior peripherals. It resembles other anterior periph- 
erals in its moderate height. 
There is little or no authentic material to throw light on the structure of the plastron of 
this species. 
A lot of bones, including portions of more than one individual, probably of more than one 
species, bears Cope’s s label “Emys pachylomus, Black Buttes.” Among them is an entoplastron 
which evidently is the one described by Cope in the Sixth Annual Report of the U.S. Geological 
