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 free 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. 383. 



Figs. 380-383. Echmatemys megaulax. Peripherals and entoplastron. Xi. 



380. Section across posterior peripheral. No. 1184 A.M.N.H. 



381. Right third or left seventh peripheral. No. 1184 A.M.N.H. 



382. Section of peripheral of fig. 381. 



383. 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 for a rib. This, like others belonging to Cope's specimens, had the sulci 

 deeply imprest. Cope's fig. 31 is almost certainly the first right peripheral and is quite dif- 

 ferent from the corresponding bone of E. euthneta, being 5.2 mm. thick where it joined the 

 nuchal, while that of E. euthneta is 9 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 eosto-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, 

 7 mm. 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 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 



