LlTTORINIDrE. 24o 



within, not nacreous, prolonged into a short canal below ; lip 

 subrostrated in the middle ; columella edentulous. Operculum 

 corneous, paucispiral. R. Souverhianus^ Fischer (Ixix, 29). New 

 Caledonia. 



LiMNOTROCHUS, E. A. Smith. Shell trochoid, umbilicated, 

 without an epidermis, spirally ridged ; aperture non-lirate within, 

 with the outer lip oblique, the basal margin broadly sinuated, 

 and the columella-edge somewhat reflexed and united to the 

 labrum above by a callosit}'. Operculum horny, paucispiral. 2 

 sp. Lake Tanganyika, E. Africa. R. Thomsoni^ E. A. Smith 

 (Ixix, 30). Remarkably like the genus Plesiotrochus described 

 above ; indeed it would be difficult to separate them, except by 

 the locality ; this, with other yqyj curious forms imitating marine 

 genera, occurs in fresh water, as above. 



MiCRODOMA, Meek and Worthen. 



Distr. — M. conica, M. and W. (Ixix, 26). 



Shell small, rather thick, conical, imperforate, composed of 

 flattened whorls, the last one of which is more or less angular 

 around the middle and little produced below ; aperture about as 

 high as wide ; outer lip simple, straight and oblique in outline ; 

 columella without folds or plications, inner lip thin and slightly 

 reflected at the base of the columella. Surface with revolving 

 nodular ridges. 



Cyclocheila, Conrad. 



Distr. — 1 sp. Tertiary ; So. America. 



Pyramidal; aperture circular; labrum expanded, columella 

 flattened, subangular at the base ; periphery angular ; a very 

 doubtful little shell, probably fresh water. 



Lacuna, Turton. 



Etym. — Lacuva, a fissure. Syn. — Temaua, Leach. 



Distr.— \^ sp. Northern shores, Norway, Britain, Spain, 

 United States. Fossil. Eocene — . L. pallidula^ Da Costa 

 (Ixix, 31). 



Shell turbinated, thin; aperture semilunar; columella flattened, 

 with an umbilical flssure ; operculum paucispiral. 



Animal. Operculigerous lobe furnished with lateral wings and 

 tentacular filaments. Teeth 5-cusped ; uncini 1, 2, dentated, 3 

 simple. Spawn vermiform, thick, semicircular. Range, low- 

 water to 50 fathoms. 



. The Lacunae feed upon sea-weed, and Loven observes that 

 when the fucus is of a brown color, the animals become green, 

 but if red, they assume a rosy tint. 



EPHERiA, Leach. Shell thin, with revolving colored bands ; 

 spire rather elevated ; inner lip thin, sharp. L. vincta, Turton 

 (Ixijt, 32). 



