240 CRETACEOUS LAMELLIBRANCHIA. 



postei-iiir I'-xtrt'iuity. On the anti'i'ior part of the sIil'U the (ii'iiaiiieutatiuii consists 

 of narrow, sliarp, concentric ribs, ■\vliicli become less distinct on the median and 

 posterior parts. 



Bemiiiis. — Only one specimen — an internal cast — has been seen. Tt i-esembles 

 A. (Gercumija) riii.ri/ifl>i, but is more inequilateral and more elongate. 



DistriJjutioii. — Upper Greensand of the Isle of Wight. 



Anatixa (Ckkcomya), sp. Plate XXXIX, fig. C. 



Imperfect specimens of a species of Anatina {Gercomya) have been found in the 

 Upper Greensand of Warminster and in the Cenomanian (Bed 10) of Dunscombe, 

 South Devon. In shape they resemble A. {Gercomya) fvoiliirtu, Zittel.^ 



Genus — Thuacia, Leach in //. M. 1). de Blaiiivilh', 1824. 

 (' Diet. Sci. nat.,' vol. xxxii, p. 347.) 



Thhacia PuiLLiPsi, lidmer, 1841. Plate XXXIX, figs. 7— U. 



1829. Mya depressa, J. Phillips. Geol. Yorks., p. 121, pi. ii, fit;. 8 (uou M. depressa, 



Sowerbv, 1823). 

 1841. Thracia FHihhipsii, F. a. Bljmer. Die Versteiu. d. uord-deutsch. Kreide- 



geb., p. 74, pi. X, fig. 1. 

 1850. — RBCVRVA, A. (VOrhiijiiy. Prodr. de Pal., vol. ii. p. 117. {'f T. snb- 



(lepressa, p. 74.) 

 1854. — Phillipsi, J. Morris. Cat. Brit. Foss., ed. 2, p. 227. 



1865. — — F.J.PictetamlG.Gampiche. Foss. Terr. CrJt. Ste. Croix 



(Mater. Pal. Suisse, ser. 4), p. 120. 

 — — EECURVA, Picfet and Ganqnche. Ibid., p. 120. 



1870. — — F. Stoliczka. Palaeont. ludica, Cret. Fauua S. India, 



vol. iii, p. 72 {Corimya V). 

 1875. — Phillipsii, Phillips. Op. cit,, ed. 3, p. 254, pi. ii, fig 8. 



1900. — Phillipsi, A. Wdllemann. Die Biv. u. Gastrop. d. deutscli. u. 



liolliind. Neoeoms (Abliaudl. d. 

 k. preussisoli. geol. Land., n. f., 

 pt. 31), p. 139, pi. vi, fig. 6. 

 1905. — — E. Harborf. Die Faima d. Seliauiuburg-Lippe"sclien 



Ivreidemulde (ibid., pt. 45), p. 77. 

 1908. — — WoUemaiiH. Jalirb. d. k. preuss. geol. Laudesaust., 



fiir 1908, vol. xxix, p. 16tj. 



Description. — Shell thin, more or less ovate in outline, moderately convex, the 

 right valve a little more convex than the left, slightly inequilateral. Antero-dorsal 



1 ' Die Bivalv. d. Gosaugeb,,' pt. 1 (1864), p. 10 [114], pi. i, fig. 6. 



