30 
SILURIAN 
Plate 3, fig*. 6. 
I.EPT.ffiNA? DETRITA. 
L. ? semiuncialis, regulariter convexa, semiovalis, obscure costata 
et striata, nec rugata. Cost® in vulva concava (solum conservata) 
circiter 13, vix striis profundis intermediis magis conspicu®, lineisque 
increment! undique decussat®. 
Half an inch wide, regularly convex ; semi-oval, with an 
even surface, without ridges. Ribs numerous; on the con¬ 
cave valve are eleven or thirteen principal ones, not much 
stronger than the three or four coarse striae which intervene 
between them. Tolerably strong lines of growth cross these. 
The shape is that of a leptosna ; but in the absence of strong 
principal ribs, and of the interior characters, it is difficult if 
not impossible to decide whether it be Leptama or Strop ho - 
mena. I incline to think it the latter, but the general appear¬ 
ance is that of the genus in which it is provisionally placed. 
Locality .—Kalajowar; 15,800 feet. (Nos. 1766-7.) 
LEPTiENA CRATERA. 
Plate 4, fig. 1. 
L. semiuncialis, radiatim-striata, transversa, valva ventrali per- 
convexa et umbone depressa ; dorsali lente concava, auriculis baud 
productis. Superficies striis crebris interlineatis, concentricis fere 
nullis. Impressiones musculares ventrales longi, ad angulum 35° 
divaricati. 
Semi-oval, the length half an inch, the width three-quarters 
of an inch. The ventral valve very convex, the dorsal slightly 
concave. The surface with fine close radiating ribs. 
The ventral valve in full-grown shells is highly convex; 
the depth of a specimen nine lines long being fully three 
lines. The old specimens are proportionally more convex than 
the younger. The greatest convexity is beyond the middle. 
The shell is pretty regularly convex, the central area only a 
little abruptly raised beyond the rest, and occasionally with a 
slight fold on it. The ears are slightly recurved, but not 
produced at all. 
