3 20 



FOSSIL TURTLES OF NORTH AMERICA. 



and ninth peripherals. The dotted line shows the position of the inguinal buttress on the inner 

 side of the shell. 



In the American Museum of Natural History there are various specimens which enable 

 us to add much to our knowledge of the structure of this species. Unfortunately, none of the 

 specimens is complete; and even when all are taken together, we are left in ignorance of much 

 of that part of the carapace behind the inguinal notch. 



Among the materials referred to are some which were collected by Professor Cope in 1872, 

 but which do not appear to have been identified by him. One of these, No. 1077, furnishes the 

 greater portion of the anterior lobe of the plastron; the hinder lobe, except the hinder ends of 

 the xiphiplastrals; and a piece (fig. 414) of the carapace consisting of parts of fourth, fifth, 

 sixth, and seventh costals and the sixth, seventh, and eighth peripherals. The remains of 

 another individual, No. 1076, somewhat larger than the type, present the second and third 

 peripherals of both sides, many fragments of costals, nearly the whole of both epiplastra, and 

 a portion of both xiphiplastrals. A third specimen, No. 1079, from Haystack Mountain, 

 Wyoming, consists of the epiplastra of a still larger individual. 



The best example of this species in the American Museum is numbered 6085, and was col- 

 lected in the Bridger beds of Wyoming, by the expedition sent out in 1893. The exact locality 

 and level are not on record. This individual lacks the whole of the carapace behind the 



414 



415. 



FIGS. 414-416. Echmatemys septaria. Carapace and plastron. 



414. Portion of carapace. Xi- No. 1077 A. M. N. H. Presents the seventh, 



eighth and ninth peripherals and portions of fourth to seventh costals. 

 Dotted line shows course of articulation of inguinal buttress on inner 

 surface. 



415. Anterior portion of carapace. Xj. No. 6085 A.M.N.H. 



416. Plastron. X}. No. 6085 A. M. N. H. 



416. 



inguinal notch; neurals and costals immediately in front of this notch are crusht and damaged, 

 but the remainder of the carapace and the whole of the plastron are in fine condition. It is ac- 

 companied by another chelonite, No. 6089, which presents the anterior two-thirds of both 

 carapace and plastron in fine condition. Unless otherwise stated the following description is 

 derived from No. 6085. 



The length of the carapace (fig. 415) can not be determined with exactness; but it was 

 close to 380 mm. The breadth was at least 210 mm. The elevation of the shell in life can not 

 now be determined. It is now 141 mm. high. The indications furnisht by the various speci- 

 mens are that the shell was quite convex. The plastron is nearly flat in the middle portion; 

 but the anterior lobe rises in front; and the hinder lobe is somewhat concave, especially near 

 the borders. 



At the sides the carapace rises from the plastron upward and outward about 57 mm., then 

 turns steeply upward, and curves toward the midline of the back. The lateral carina on the 

 bridge peripherals is obtuse. There is no dorsal carina; nor is the carapace especially 

 flared upward at the sides in front. 



