148 MANUAL or THE MOLLUSC A. 



Shell elongated, many-wliirled ; wkii-ls variously sculptm-ed, and zoned 

 like pleurotomaria ; apertui'e slightly channelled in front ; outer lip deeply 

 notched. 



The mui'chisoniee are characteristic fossils of the palaeozoic rocks ; they have 

 been compared to elongated pleurotomarise, or to cerithia ^^'ith notched aper- 

 tiu'es ; the fii-st suggestion is most probably correct. 



Fossil, 50 sp. L. silm-ian —Permian. N. America, Eui'ope. 

 Teochotoma, Lycett. 



Etyra., troclms, and tome, a notch. 



Syn., ditremaina, D'Orb. 



Type, T. conuloides. PL X., fig. 26. 



Shell trochiform, slightly concave beneath ; whirls flat, spirally striated, 

 rounded at the outer angles ; lip with a single perforation near the margin. 



Fossil, 10 sp. Lias — Coral Rag. Brit., France, &c. 



? CiKKUS, Sowerby. 



Etym., cirrus, a curl. 



Tyi^e, C. nodosus, Shy. Min. Con. t. 141 and 219. 



Shell sinistral, trochiform, base level ; last whirl enlarging rather more 

 rapidly, somewhat irregular. 



Fossil, 2 sp. Inf. oolite, Bath oolite. Brit., France. 



This genus was founded on a plem-otomaria, a euomphalus, and C. nodosus. 

 (v. Min. Con.) It is stiU doubtful what species may be referred to it. 



Fig. 89.* 



Ianthixa, Lam. Violet-snail. 



Etym., ianthina, violet-coloured. 



Type, helix ianthina L. (I. fragilis. Lam.) PI. X., fig. 27. 



Shell thin, translucent, trochiform ; nucleus minute, styliform, sinistral ; 

 whirls few, rather ventricose ; apertm-e four-sided ; columella tortuous ; lip 

 thin, notched at the outer angle. Base of the sheU deep \-iolet, spii'c nearly 

 white. 



Animal:— head large, muzzle-shaped, with a tentacle and eye-pedicel on 



* Fig. 89. Ianthina fragilis, Lam. (from Quoy and Gaimard). Atlantic, a raft, 

 i> egg capsules, c gills, d tentacles and eye-stalks. 



