OF SOUTHERN INDIA. 473 



10. OsTREA ZiTTELiANA, StoUczlm, PI. XLIV, Fig. 4. 



Ost. ohlique rotimdate suh-qucalrangnlari, compressa, snb-CBquivalvi, valvis mar- 

 ginibus carcUnaUbns longis, antice rectiusctilis, postice oblique descendentibus, instruc- 

 tis, in sttperficie concentrice sub-costnlatis et sidcatis, valv. inferiore cdtera pauhdnm 

 convexiore et crassiore, prope timhonem affixa ; nmbone obtuse 2'>'>'ojiciente, intus fossula 

 ligamentcdi excavata instructo ; valva sup. tenuiore, mnboue vix promimilo, area 

 Ugamentali angusta, medio vix depressa. 



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

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

 Chalmasia (VulsellaJ 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 difi'ers from ZitteUana 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 

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

 from that of other Ostrea;. 



Locality. — Vylapaudy, in a brownish sandstone. 



Formation. — Arrialoor group. 



XLVI. Family— ANOMIID^F. 



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 laminse 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 ai'e 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 thickened 



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