igoo] Lambe — Notes on a Turtle. 65 



where they and the abdominals meet a series of inframars:inals 

 that overlap the peripheral bones. All the sulci are deep and very 

 conspicuous except those marking- the position of the infra- 

 marg-inals, the inner anterior boundaries of the gulars, and the 

 division of the inter^ular. These latter, however, are sharply and 

 clearly defined. The sulural line between the hypoplastrals and 

 the xiphiplastrals is shown in the smaller of the two specimens. 

 As regards the sculpture, the original description is accurate and 

 succinct. 



Turning to the dorsal or upper side of the plastron (fig. 2, plate 

 III) it is seen that the rugose sculpture extends inward for some 

 distance from the free edges of the lobes, more particularly at the 

 extreme anterior end, where also the bone is very much thickened. 

 A decided thickening also occurs in the axillary region. The oval 

 outlines on the xiphiplastrals (P, plate III) show the position of 

 smooth, slightly raised, flat surfaces that are apparently facets for 

 the articulation of the pubic bones. 



• In the two marginal bones collected by Mr. McConnell the 

 rib prolongations from the adj-ic^nt costal bones are preserved. 

 These marginals, with parts of costal bones collected by Dr. 

 Dawson, show that the carapace had a sculpture similar to that 

 of the plastron, and was covered by well-developed shields. The 

 rib-heads of the costals were apparently also well-developed. 



The foregoing characters indicate a Chelonian that cannot be 

 retained in the genus Compsemys, which is nearly allied to Pleiiro- 

 sternon and possesses a mesoplastral element. The presence of 

 two small gular shields separated by a divided* or double inter- 

 gular shield (in reality two intergulars), and of a series of infra- 

 marginals, the absence of a mesoplastral and of a sutural union of 

 the pelvis with the plastron, together with an abbreviation of the 

 lobes and a decided lengthening of the sternal bridge are charac- 

 ters that suggest such close affinities to the genus Adocus of Cope 

 that this species is here referred to that genus. 



Measurements : 



M. 

 Estimated length of plastron (28^ inches) 720 



*G. Baur, Proc. Acad. Nat, Sci. Philadelphia, vol. xliij^, 1891, p. 428. Th^ 

 genus Adocus. 



