216 MOLLUSCA FROM THE CRAG. 



CYTHEREA LINCTA. Lam. An. sans Vert., t. v, p. 573, 1818. 



1 Basterot. Bord. Foss., p. 90, pi. vi, fig. 10, 1825. 



Phil. En. Moll. Sic., vol. i, p. 41, voh ii, p. 32. 



Dujard. Mem. Soc. Geol. de France, t. ii, part ii, p. 260, 1837. 



Bronn. Leth. Geogn., p. 955, t. xxxviii, fig. 4 a c, 1838. 



SINUATA. Turt. Brit. Biv., p. 163, 1822. 

 ASA LINEATA. Leach, MSS. Defrance, Coll. ex Basterot. 

 EXOLETA LINCTA. Brown. Illust. Brit. Conch., pi. xx, fig. 4, 1827. 

 ARTEMIS Forbes. ^Egean. Invert. Rep. Brit. Assoc., p. 180, 1843. 



Loven. Ind. Moll. Scand., p. 39, 1846. 



Forb. and Hani. Hist. Brit. Moll., vol. i, p. 431, pi. xxviii, figs. 5, 6, 1848. 



SINUATA. S. Wood. Catalogue, 1840. 



COMPTA. Loven. Ind. Moll. Scand., p. 39, fide Alder. 



ARTHEMIS LINCTA. Agassiz. Icon, des Coq. Tertiares (Extr. des Nonv. Mem. de la Soc. 



Helv. des Sc. Nat., tome vii, 1845,) p. 22, t. iii, figs. 1114. 

 DOSINIA LINCTA. Gray. List. Brit. Moll., p. 4, 1851. 

 Lister. Hist. Conch., lib. iii, fig. 126. 



Spec. Char. Testa suborbiculari, lentiformi, svMncequilaterali, concentrice stria id 

 striis numerosis, confertis Icevibus ; lunuld cordatd impressd. 



Shell suborbicular, lentiform, subinequilateral, fragile, covered with numerous 

 close set striae : lunule heartshaped ; impression of the mantle with a deep tongue- 

 shaped sinus. 



Diameter, \\ inch. 



Localities. Cor. Crag, Sutton, Ramsholt. 



Red Crag, Walton-on-the-Naze. 



Recent, Mediterranean, British and Norwegian Seas. 



Not very rare either in the Coralline or in the Red Crag, but the specimens are in 

 general extremely fragile and very difficult to procure ; they are much thinner than 

 those of the preceding species, and appear to have less of animal matter remaining ; 

 although this is much less abundant than A. lentiformis, it appears to present a greater 

 diversity of character in the outline, and I have thought it necessary that two forms 

 should be represented : where individuals have become more elongated than what 

 'might be considered as the normal form of the species the shell is invariably more 

 convex or tumid, so that an equal quantity of space is occupied by the animal. 



It is said in the recent state in the British seas to have a range in depth varying 

 from low water mark to the depth of sixty fathoms. 



Mr. Smith, of Jordan Hill, enumerates Cytherea exoleta in his Catalogue of Shells 

 from the Clyde Beds. Mem. Wern. Nat. Hist. Soc., v 1. viii, p. 45, 1838. 



