302 TEETIAET VEETEBEATA OF THE EATtTM. 



Plastron (cont.) : 



Length of entoplastral bone 8'7 



Width of entoplastral bone 8'7 



Length in middle line of hyoplastral 7'5 



„ „ hypoplastral 11 



„ „ xiphiplastral 9-5 



Length of inlergular shield 8 



R. 3345. Anterior portion of plastron, showing the thickenings on the inner face of the epiplastrals. 

 Width of anterior lobe 22 cm. ; length of ditto in middle line 8'2 cm. ; length of 

 entoplastral 6 "8 cm. 



R. 3200. Anterior portion of plastron : the form of the entoplastral is rather different from that 

 seen in the other two specimens^ being more escutcheon-shaped. Width of anterior 

 lobe of plastron 19 cm. app. ; length of ditto in middle line 8 cm. ; length of ento- 

 plastral 6 cm. app. Presented hy W. E. de Winton, Esq., 1903. 



K. 3347. Proximal half of a left humerus of a medium-sized tortoise, provisionally placed here. 

 This specimen is similar to the humerus of Podocnemis, except that the ulnar crest is 

 less developed and the head less rounded, though this latter character may be due to 

 partial abrasion. 



Stereogenys libyca, Andrews. 



[Text-fig. 97.] 



1903. Stereogenys lihyca, C. W. Andrews, Ann. & Mag. Nat. Hist. [7] vol. xi. pp. 115-119, pi. vii. 

 1903. „ „ A. von Reinach, Abhandl. Senckenberg. naturf. Gesell. vol. xxix. pt. 1, 



pp. 41-45, pi. xii., pi. xiii. figs. 1, 6-9. 



Ti/pe Specimen. — A nearly complete shell (text-fig. 97) ; British Museum. 



This species is distinguished from 8. cromeri by possessing a more convex shell, 

 somewhat expanded posteriorly, and a nuchal bone considerably wider than the first 

 vertebral shield. From 8. podocnemioides it differs in having the humeral shields 

 widely separated posteriorly by the intergular. 



Form. & Log. — Fluvio-marine beds (Upper Eocene) : north of Birket-el-Qurun. 



The specimen (text-fig. ■ 97) upon which this species is founded is a very well- 

 preserved shell, wanting only a portion of the left side of both the carapace and 

 plastron ; the pelvic bones were found in situ in the shell. Although cracked in 

 all directions this specimen seems to be quite undistorted and gives a good idea of 

 the form of the living animal. In its general form the shell is very like that 

 of Podocnemis madagascariensis, but rather more convex, particularly in the region 

 covered by the last vertebral shield, where there is a well-marked prominence. The 

 carapace is somewhat expanded posteriorly. 



There are seven neural bones (text-fig. 97, A), the series being separated from the 

 nuchal in front and from the suprapygal behind by the union in the middle line of 



