258 CRETACEOUS PELECYPODA 



imclulating or divaricate striation, which is quite independent from the striae indi- 

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

 numerous and only slightly curved, hut 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 [Myrtea] arcotina, Stoliczka, PL XV, Figs. 1-5. 



L. [Myrtea^ testa traioezoidali, longiore qiutm alta, compressiuscula , marcjine 

 Itmulari pmilulum insimiato, valde declivi, areali levissime convexo, antice sub- 

 rotundata, j^ostice oblique truncata ; svperjicie striis concentricis confertissimis et 

 nonnnllis distantioribvs iticrassatis tecta ; lunula et area elongatis, excavatis, angustis ; 

 cardiiie dentlbus cardinulibus et lateralibus bene distinctis instructo ; margine interna 

 plus minusoe distincte crenidato. 



Height of shell : its length... ... ... ... 0-75-0-81 



Thickness „ : „ ... ... ... ... 0-36 -O'SO 



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 veiy precijiitously and is slightly concave, the upjier 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 svu"face is covered with numerous strise of growth, near the apex all are 

 strongei', 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. — Parally (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. — Ootatoor, Trichinopoly, and Arrialoor groups. 



6. LuciNA [Myrtea] dentigera, Stoliczka, PI. XT, figs. 6-8. 



L. [^3Iyrt.'\ testa sub-quadrangulari, crassiuscula, tumida, margine lunulari 

 concavo, areali rectiusculo ; lunula lata, ovate elongata, profunda, area ])aulo exca- 

 vata, angustiore ; superficie concentrice lamellose confertim striata, margine interna 

 crasse dentato. 



Height of shell .about equal to its length. 



Thickness nf same : its length ... ... ... ... 0"71 



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 striae ; the inner margin is particularly in some 



