28G 
TERTIAET VEETEBRATA OF THE FAYt^M. 
In the ])lastron the clifiercnces between the two sjjecies are considerable. Thus 
in the present species the length of the bridge is about half the length of the plastron 
in the middle line, in T. ammon it is usually less. In consequence of this the 
anterior and posterior lobes of the plastron, particularly the former, are relatively 
shorter. The median portions of the epiplastrals [Ep.p.) are produced forwards into 
a pointed anterior projection ; in T. ammon, when this projection is present at all, 
it is truncated. The posterior lobe of the plastron narrows more towards its distal 
(uid, and the anal region is scarcely at all marked off by the notch or groove which is 
SC) strongly defined in T. ammon. Lastly, the groove between the femoral [ fern.) and 
anal [an.) shields slopes more backwards. It may be added that the whole shell 
appears to have been less solidly built than in T. ammon. This species is named 
after Mr. H. J L. Beadnell, by whom the type specimen was found. 
Form, cf Log. — Fluvio-marine beds (Upper Eocene) ; north of Birket-el-Qnrun. 
C. 8773. Shell of which the carapace is somewhat imperfect. Type specimen described and figured 
above. The dimensions (in centimetres) of this specimen are : — 
Length of carapace in middle line 75-1 
,, plastron in middle line tjG-4 
„ to end of xipliiplastra 71'G 
AYidth of anterior lobe 33 app. 
Length of anterior lobe ^ IS apj). 
Width of posterior lobe 32-5 
Length of posterior lobe 21 app. 
„ bridge 33 
Height of shell 35 app. 
Testudo isis, sp. nov. 
Type Specimen . — An imperfect shell, wanting the posterior marginals ; Geological 
Museum, Cairo. 
This species is founded on a comparatively small rounded shell in which the growth- 
lines of the bones are strongly marked, forming in places [e. g. on the costals) 
prominent ridges. The areas covered by the vertebral shields are not inflated and 
pass smoothly into the costal region. The neural bones are all hexagonal, with the 
antero-lateral sides the shortest. There is a very narrow nuchal shield. 
The anterior end of the plastron is rounded and nj)tnrned, but is not greatly 
thickened as is the case in the carapace of the female of T. ammon (see Plate XXIV.). 
The posterior end of the plastron forms a wide open notch ; the areas covered by the 
anals are sharply separated from the region in front. 
The presence of the strongly marked growth-lines probably indicates that this is 
a young animal, but the fact that all the neurals are hexagonal seems to exclude 
