NO. 2292. 



NEW FOSSIL TURTLES— GILMORE. 



127 



the plastron lacks the entoplastron and the greater parts of the 

 epiplastra, also much of the lateral borders of the posterior lobe. 



The carapace as now preserved is highly arched transversely, the 

 front of the shell descends quite rapidly from the posterior end of 

 the first neural to the nuchal scute. The contour of the anterior end 

 is broadly rounded and without median emargination. It is esti- 

 mated that when complete the shell had a greatest length of about 

 135 milhmeters. The carapace presents a smooth undulating surface, 

 except for the growth lines of the horny scutes that formerly covered 

 the peripherals and costals. I find similar growth markings on the 

 typical specimens. Immediately outside of the costo-vertebral 

 sulci, the costals are strangely swollen, a feature in which this species 

 resembles Echmatemys testudinea (Cope). Cotype No. 4121, U.S.N .M., 

 which has the sixth costal of the left side present, clearly indicates 

 the presence of this swollen "hump." The sulci run in grooves, but 

 where they cross the posterior neurals they are abruptly and deeply 

 impressed, as in some of the typical specimens. 



The nuchal is angularly convex transversely. It is 28 milli- 

 meters long; 22 millimeters wide on the free border, which is acute. 

 The greatest breadth is 35 millimeters. 



The neurals posterior to the first, which is suboval, are all hexag- 

 onal, with the widest end forward. The posterior neurals (sixth, 

 seventh, and eighth) are keeled. It will be noted from the table of 

 measurements that all of the neurals except the first are wider than 



long. 



Measurements of neurals, in millimeters. 



« Estimated. 



The median costals are remarkably uniform in the width of the 

 proximal and distal ends. Their upper ends as mentioned previously 

 are conspicuously swollen outside of the deep costo-vertebral sulcus. 

 Except at the swoUen portion the costals are comparatively thin. 

 The distal end of the fifth measures but 4 millimeters in thickness. 

 On the inner surface of the first costal the sutural scar for the 

 axiUary buttress is 5 millimeters wide and 17 millimeters long. 



It extends about halfway up to the midline of the shell. The 

 posterior buttress articulates about equally with the fiifth and sixth 

 costals, but extends upward only about halfway to the center of the 



