THRACIA. 243 



(lifRcult. especially without the opportunity of comparing specimens, to establisli 

 the identification. Professor Boule informs me that the type is a poorly preserved 

 specimen, but that its outline is satisfactorily represented in (rOi'bio-ny's fio-ure; 

 the specimen is now in tJie Natural History Museum, Paris. T. Iu>huuihlina is 

 allied to T. mocomiensls (d'Orbigny),' but is said to differ from tlic latter l)y the 

 greater curvature of the ventral margin and by its relatively sliorter shell. 



Distrihatiou, — Lower Greensand (7V/;/r(-l)cd and Crackers) of Atherfield. 

 Atherfield Reds of Redhill, Reigate. 



'i'iii;A('iA Sano'X\e-Crucis, ridet civd Cdnqiirln-, 18()5. Plate XL, tigs. 4 (i. 



1865. Thracia SANCTiE-CRrcis, F. J. Pirli^t ami G. Campirh,-. Foss. Terr. Crot. 



Ste. Croix (Mater. Pal. Suisse, ser. 4), 

 p. 117, pi. cviii, fio-. 8. 



1870. — — F. Stoliczht. Palseont. Iiulica, Cret. Fauna S. 



India, vol. ill. p. 72. 



Description. — Shell oblong, compressed, inequilateral. Anterior margin 



rounded; ventral mai'gin slightly curved; posterior margin truncated, slightly 



convex, forming an angle with the postero-dor.sal margin. A carina e.xtends in a 



curve from the umbo to the postero-ventral angle and cuts off a concave postero- 



dorsal area. The surface of the shell is ornamented with growtli-rings. 



Measurements : 



(1) (-') 



Length . . 43 . 3'.) mm. 



Height . . 20 . Ki „ 



(1) Gault, Folkestone. 



(2) Gault, Black Veu. 



Aijiuih'ea. — It seems doubtful whethei- this species is distinct from 2\ siviplex 

 (d'Orbigny), of which casts only are figured by d'Orbigny- and by Pictet 

 and Campiche^; but the latter authors state that it differs from T. siuqilcr by the 

 absence of an internal rib, the })resence of a carina, and by the more acuminate 

 anterior end. 



Ti/jye. — From the LTpper Gault of Ste. ('roi.\. 



I >isti'iliiiti(iii. — Gault of Folkestone and iJlack ^'en. 



Tiii;.\(iA, sp. i'late .\l>, figs. 7 — '.». 



Some examples of Tlinicia, usually of rather large size, apjiear at first .sight to 

 be distinct from T. Smicfie-Gritcis on account of their i-elatively greater height and 



1 'Pal. Frane. Terr. Cri't.,' vol. iii (1845), p. 381, pi. cei-lxxii, fi>.;s. 3, 4. Pictet aud Cauipiche, 

 op. cit., p. 11-5, pi. cviii, fij^s. 3, 4. 



- Op. cit., p. 382, pi. ecelxxii. flip's. .5, ti. 



8 ' Foss. Terr. Crc't. Ste. Croix " (' Mater. Pal. Suisse,' ser. 4, 1865), p. 116, pi. iviii. fii;. 7. 



