258 CEETACEOUS PELECYPODA 



undulating or divaricate striation, which is quite independent from the stride indi- 

 cating stages of growth. In the present species the longitudinal striae are very 

 numerous and only slightly curved, but the total form of the shell exactly corres- 

 ponds to that of its recent and cainozoic allies. 



Locality, — Ninnyoor, in white limestone ; apparently rare. 



Formation. — Arrialoor group. 



5. LuciNA [Myetea] arcotina, Stoliczka, PL XV, Eigs. 1-5. 



L. [_Myrtea'\ testa trapezoidali, longiore quam alta, compressiuscula , margine 

 Itmulari paululum insinuato, valde declivi, areali levissime convexo, antice sub- 

 rotundata, postice oblique truncata ; superjicie striis concentricis confertissimis et 

 nonnullis distantioribus incrassatis tecta ; lunula et area elongatis, excavatis, angustis ; 

 cardine dentibus cardinalibus et lateralibus bene distinctis instructo ; margine interno 

 plus minusve disthicte crenulato. 



Height of shell : its length... ... ... ... 0-75 -O'Sl 



Thickness „ : „ ... ... ... ... 0-36- 0-50 



This species has very much the form of "the type species of Myrtea, Luc, spini- 

 fera, Mont., and the hinge is also quite similar, so that there can be no doubt as 

 to the sub-generic determination of the species. It is always longer than high, the 

 lunular margin slopes very precipitously and is slightly concave, the upper or areal 

 margin nearly straight or slightly convex, the edges being rather sharpened and 

 somewhat prominent ; both lunula and area are deeply excavated and elongated ; 

 the surface is covered with numerous striae of growth, near the apex all are 

 stronger, but further on only a few are more prominent at certain distances, and 

 separated by deep sulci. In some of the specimens I have not been able to observe 

 any crenulation of the internal margin, in others it is, however, distinct. 



Localities. — Paraliy (one specimen from a dark colored earthy limestone) ; 

 Andoor (two specimens in a grey conglomeratic sandstone) ; Olapaudy (two speci- 

 mens in a light brown oolitic rock). 



Formations, —Ooi^iooY, Trichinopoly, and Arrialoor groups. 



6. LuciNA [Myrtea] dentigeua, Stoliczlm, PI. XV, Figs. 6-8. 



L. \_Myrt,'] testa sub-quadr angular i, crassiuscula, tmnida, margine lunulari 

 concavo, areali rectiusculo ; lunula lata, ovate elongata, profunda, area paulo exca- 

 vata, angustiore; superficie concentrice lamellose confer tim striata, margine interno 

 crasse dent at o. 



Height of shell about equal to its length. 



Thickness of same : its length ... ... ... ... 071 



The more regularly quadrangular and at the same time more tumid form 

 readily distinguish this species from the previous one. The surface is covered with 

 concentric, sharp, equal lamellar strise ; the inner margin is particularly in some 



