312 



FOSSIL TURTLES OF NORTH AMERICA. 



No. 5987 of the American Museum is referred to this species, altho it presents some impor- 

 tant differences. It is represented by a damaged shell from Grizzly Buttes. Its size is almost 

 exactly that of No. 5988. The carapace differs especially in having the 

 costals modified so that their distal ends are alternately wider and nar- 

 rower. The proximal ends are not present. The dimensions of the costals 

 are shown in the table herewith. 



The plastron is thick and heavy, the thickness of the bones at the 

 crossing of the longitudinal median suture with that between the hypo- 

 plasia and xiphiplastra being 18 mm. The anteriorjobe has the same 

 proportions as in No. 5988, but its width is slightly greater. The thick- 

 ening on the upper side of the lip extends back 22 mm., thus being wider 

 than in No. 5588, but the lip above and below resembles closely that of 

 the type of Emys jeanesi. The hinder lobe is wider than in No. 5588, 

 being 150 mm. The beveled surface on the upper side of the lobe has a width, at the hypo- 

 xiphiplastral suture, of 26 mm. The inguinal [scute] |runsTor 'a shoiVjdistance between the 



43- 



Figs. 402 and 403. Echmatemys wyomingensis. Carapace and plastron. X J- 

 Yale University Museum. 



402. Carapace showing supernumerary neurals, costals, etc. 403. Plastron. 



abdominal scute and the sixth marginal. It is possible that in this specimen we have a dis- 

 tinct species, but the differences are probably due to individual variations. 



No. 5950 of the American Museum, collected in 1903, at Grizzly Buttes, Wyoming, pre- 

 sents a portion of both carapace and plastron, both badly crusht. The specimen is peculiar 

 in the form of the first vertebral scute. This is longer than in No. 5988 and much narrower in 

 front. The length is 77 mm.; the width in front, 60 mm. The lateral sulci bounding this scute 

 meet the first marginals at the middle of the length of the latter. 



No. 5968 of the American Museum was collected in the western portion of Grizzly Buttes. 

 It furnishes a good plastron, various fragments of the carapace, some limb bones, and the right 

 dentary. The plastron has a total length of 306 mm. The specimen is valuable on account 

 of the dentary bone. It establishes the fact that the triturating surfaces of the jaws were 

 smooth and very narrow. Fig. 398 represents the left dentary as seen from the side and fig. 

 399 as seen from above; both of the natural size. A little of the bone at both extremities of this 

 dentary is missing. The portion remaining is 24 mm. long. The triturating surface is hardly 



