120 Dr. C. W. Andrews oii some 



cannot be made out. The nuchal l)one is large and its 

 anterior border is emaroinate. 



Scarcely any trace of the outlines of the epidermal shields 

 remains, but the two middle vertebrals seem to have been 

 large and roughly hexag'onal in outline. 



The Plastron (PL VIIT. tig. 1, B) —The plastron Is large ; 

 its total length is about 44 centim.; the length of the bridge 

 is 20*5 ; the width of the anterior lobe 24 ; the width of the 

 posterior lobe 24. The entoplastron [Ent.) is large and 

 rhomboidal, and the sutures between the epi- and hyoplas- 

 trals running out from its outer angles terminate on the edge 

 of the plastron in the groove between the humeral and 

 pectoral shields, as in the last species. The suture between 

 the hyo- and hypoplastrals {Hy.p. and Hyp.p.) crosses tlie 

 middle of the bridge and terminates in the inner angles of 

 the small rhomboidal mesoplastrals {Ms ]j.), which are wedged 

 in between the marginals and the outer ends of the hyo- 

 and hypoplastrals. The position of the suture between the 

 hypo- and xiphiplastrals is shown in fig. 1 B, PI. VIII. 

 The posterior portion of the plastron seems to have been 

 notched much as in Stereogenys Uhyca, but none of the 

 specimens are quite complete in this region. 



The arrangement of the horny scutes in the plastron is 

 similar to that seen in S. lihyca^ theintergular [ig) being very 

 large and separating both the gulars {g.) and the humerals {n.) ; 

 it extends as far back as the middle of the entoplastron. The 

 other shields present no important peculiarity so far as can be 

 seen. As remarked above, there can be little or no doubt that 

 the Ciielonian just described and Stereogenys Uhyca belong to 

 the same genns ; but there is some doubt as to whether the 

 shell here referred to S. Crow?er/ really belongs to that species, 

 the type of which is a skull and mandible (see Geol. Mag. 

 1901, p. 442). Although, however, the skull has never been 

 found actually associated with the shell now described, the 

 probability that they belong to one and the same animal is so 

 great that it is certainly advisable to refer them to one species 

 until the contrary can be proved. 



Podocnemis antiqua, sp. n. (PI. VIII. fig. 2, A & B.) 



Another Pleurodiran tortoise of smaller size was collected 

 from the Middle Eocene beds. This species differs con- 

 siderably from that just described both in its general form 

 and in some points in the structure of its shell. The carapace 

 is shorter and broader and more highly arched anteriorly ; the 

 nuchal border is quite straight, there being no trace of any 

 emargination. Posteriorly the carapace is less convex and 



