OP SOUTHERN INDIA. 473 



10. OsTREA ZiTTELiANA, StoUczIm, PL XLIV, Pig. 4. 



Ost, oblique rotundate suh-quadrangular% compressa, suh-mquwalm, valvis mar- 

 ginihus cardinalibus longis, antice rectmsGulis, postice oblique descendentibus, iMstme- 

 Us, in superficie concentrice sub-costulatis et sulcatis, valv. inferiore altera paululum 

 convexiore et crassiore, prope umbonem affixa; umbone obtuse projiciente, intusfossula 

 ligamentali excavata instructo ; valva sup, tenuiore, umbone vix prominulo^ area 

 ligamentali angusta, medio vix depressa. 



Only the single figured specimen has been found of this interesting shell, 

 which is closely allied to Zittel's Ostrea Madelungi, identified by Coquand with 

 Chalmasia (Vulsella) Turonensis of Dujardin (see p. 397). I do not think that 

 the identification of Zittel's species is correct, though it does not show any place of 

 attachment on either of the valves. O. Madelungi differs from Zitteliana by having 

 the concentric ribs obliquely distinctly quadrangular, while in the Indian species the 

 concentric sulcations are distinctly rounded and the posterior cardinal edge is not so 

 much prolonged and so straight as the anterior. Our specimen shows a triangular 

 ligamental area with a median groove in the lower valve and a very narrow and flat 

 ligamental area in the smaller valve. The structure of the shell does not differ 

 from that of other Ostrece. 



Locality, — ^Vylapaudy, in a brownish sandstone. 



Formation. — Arrialoor group, 



XLVI. Family,— ANOMIIDu^, 



The animal of Anomia, and of its close allies, has the mantle margins quite 

 separated, except at the hinge, its edges provided with one to three rows of fine 

 cirri or filaments ; one pair of curved gills on each side, unsymmetrical, united poste- 

 riorly, each of the outer laminae furnished with a broad reflexed and free margin ; 

 palps small, striated, or almost obsolete ; lips elongated, narrow, thin ; foot short, 

 sub-cylindrical, somewhat expanded at the end ; byssal muscle strong, attached by 

 two unequal branches to the convex valve and passing through a foramen of the 

 other valve, sometimes secreting a shelly or horny lamina at the end, or a byssus ; 

 adductor muscle small, sub-central, its impression sometimes partially confluent 

 with the usually larger and sub-equal pedal scars ; a small impression also exists 

 near the beaks, it is said by Woodward to be produced by the gill-suspensor, 

 though . that muscle rather supports the lips than the gills ; pallial line continuous ; 

 the sexes are said to be distinct, ovary extending into and partially combined with 

 the right mantle lobe ; ventrical free, not passed through by the rectum. 



The shells are of an irregularly ovate or roundish shape, much depending upon 

 the form of the object to which they attach themselves, inequivalve, upper valve 

 always more or less convex, lower mostly flat, or concave, sometimes smaller and 

 thinner than the other one, with a more or less complete perforation near the beak, 

 (sometimes closed ? in adult state) ; ligament internal, attached to a thickene4 



5z 



