302 
TERTIAET VEETEBEATA OE THE EATOM. 
Plastron (cont.): 
Loiigth of entoplastral bone . . 
W'idtb of entoplastral bone . . 
Length in middle line of byoplastral 
„ ,, hypoplastral 
,, „ xipbiplastral 
Lengtli of intergular shield . . . . 
8-7 
8-7 
7-5 
11 
<)-5 
8 
R. 3345. Anterior portion of plastron, showing the tliickenings 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 G'8 cm. 
E. 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 () cm. app. Prexented htj TE. P. de Winton, Esq., 1903. 
R. 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 uluar crest is 
less developed and the head less rounded, though this latter character may he due to 
partial abra.sion. 
Stereogenys libyca, Andrews. 
[Text-fig. 97,] 
1903. Sterengentjs llhj/ca, C. Wh Andrews, Ann. & Mag. Nat. Hist. [7] vol. xi. pp. 11.5-119, ph vii. 
1903. „ „ A. von Peinach, Abhandl. Senckenberg. naturf. Ge.sell. vol. xxix. pt. 1, 
pp. 41-45, pi. xii., pi. xiii. figs. 1, G-9. 
Type Specimen. — A nearly complete shell (text-tig. 97); British Museum. 
This species is distinguished from S. cromeri by possessing a more convex shell, 
somewhat expanded posteriorly, and a nuchal bone considerably wider than the first 
vertebral shield. From S. podocnemioides it differs in having the humeral shields 
widely separated posteriorly by the intergular. 
Form. & Loc. — 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 ))ortion of the left side of both the carapace and 
plastron ; the pelvic bones w-ere found in situ in the shell. Altliough cracked in 
all directions this specimen seems to be quite uudistorted and gives a good idea of 
the form (ff’ the living animal. In its general form the shell is very like that 
of Podoaiemis madar/ascariensis, but rather more convex, particularly in the region 
covered by the last vertebral shield, where there is a well-mai'ked ])rominence. The 
cara])ace is s(jmewhat expanded posteriorly. 
Tdi(,‘re are seven neural bones (text-fig. 97, A), the series being separated from the 
nuchal in front and from the snpra])ygal behind by the union in the middle line of 
