204 
railTIART A'ERTEBllATA OF THE EAYtlM. 
oval ill outline and sliglitly udder jiosteiiorly than anteriorly; its convexity is not very 
great, thongli the crushing-, which has resulted in the breaking away of a part of the 
anterior border and the dislocation of some of the bones, may be to some extent 
res))onsible for the flattened form of the shell. There are six neurals (N.), of which the 
anterior five are hexagonal, -with the antero-lateral borders much the shortest; the 
sixth (.N. (i) is ])cntagonal, its posterior angle being thrust between the anterior part of 
the sixth costals, which behind it meet one another in the middle line, as also do the 
seventh and eighth costals. The nuchal bone seems to have been wide, but is badly 
])resorved. The suprajiygal 1) is triangular, with the postero-lateral angles 
truncated for union with the last pair of marginals ; the pygal (P^. 2) is nearly as 
wide as long. The vertebral shields (v.) are hexagonal, with the anterior and posterior 
liorders convex forw'ards. Both in its general form and in its structure the carapace 
is very similar to that of P. madcKjascariensis. 
In outline the anterior part of the plastron (text-fig. 94, B) is like that of the type 
specimen, but the entoplastron is rather longer, the postero-lateral borders being 
longer than the antero-lateral ones. The sutures between the epiplastrals {Ep.p.) and 
hyoplastrals {Uy.p.) are strongly concave forw-ards. The posterior ends of the humeral 
shields (/'.) do not reach so far back as the middle of the entoplastral, and the 
grooves between them and the pectoral shield [yeef.) do not curve backwards, and 
so do not cross the suture between the epiplastrals and hyoplastrals. The small 
mesoplastra {Ms.p.) are roughly hexagonal in form ; the xiphiplastrals {Xi.p.) are 
incom])lete posteriorly, but the hinder border of the plastron was clearly deeply 
notched. The median sutures betw-ecn the hyoplastra, the hypoplastra, and the 
xi)diiplastra w’ith one another are almost equal in length. The dimensions of this 
shell are given below'. 
C. 10202. Anterior portion of plastron. Typo specimen figni-ed and described in Ann. & Mag. 
Kat. Hist. [7] vol. xi. (1003) ]>. 121, ])1. viii. tig. 2 c, the figure being rejiroduced as 
texi-fig. 1)3. The dimensions (in centimetres) of this specimen are approximately ; — 
AVidth of anterior lobe immediately in front of bridge . . . ll-o 
Length of anterior lobe T’o 
„ entoplastron 3-7 
C. 8tC9. Anterior portion of ]ilastron. In this the humero-jiectoral groove' does not cross the 
sntnre between the epi- and hyojdastral bones, but terminates with it on the lateral 
border. The entoplastral is long; its postero-lateral sides are convex. The a])])roximate 
width in front of the bridge is l2-r) cm., the length of the anterior lobe b'.b cm., the 
length of the entoplastron 4-7 cm. 
E. 3103. Anterior jiart of jdastron similar to the ty ])0 s]»ecimen, except that the sntnre between the 
e|)i- and hyo])lastral bones is more concave I'orwards and jnst touches the hnmero- 
pectoral groove on the border of the plastron; the entoplastral is larger and its jiostero- 
lateral borders are convex. 
