298 LITTOEINID^. 



Rissoa mimita. 



Pig. 171. 



Shell minute, elevated, conic, thin, smooth, yellowish-green ; whorls five, con- 

 vex ; suture distinct. 



Turbo miiitiliis, Tottent, Sillim. Journ. xxvi. 369, fig. 7. 



Cnxjii/a minuta, Gould, Inv. Isttd. 265, fig. 171. — De Kay, N. Y. Moll. 110,pl. 4, fig. 117. 



Rissoa minuta, Stimpson, Check Lists, 4. 



Paludina sla^/nalis [foniia ventr.), Middendoef, Reise, 34. 



Shell minute, ovate-conic, elevated, obtuse at apex, thin, yellow- 

 ish-brown, or dark horn color when containing the animal ; usually 

 coated with a dark green j^igmeiit, or some minute vegcta- 

 Fig. 566. IjIq . ^^.jj^i-i^ f[yQ_^ convex, faintly wrinkled by the lines of 



growth, the two upper ones forming an obtuse apex, and 

 the lowest less than two thirds the whole length of the 

 shell ; suture distinct, with a slight shoulder to the whorl 

 R.7mnuia. ^^^^^' ^^' '^ apcrturc about one third the length of the shell, 

 oval, the lips united in mature shells by a loosely attached 

 enamel, which rises before an umbilical pit ; operculum horny, sub- 

 spiral. Length of large s])ecimens, three twentieths of an inch ; 

 breadth, one tenth of an inch ; divergence, twenty-eight degrees. 



Animal ; head proboscidiform, dusky-brown or blackish, half as 

 long as the Vjlack-tipped tentacula ; eyes on a partial peduncle or 

 dilatation on the exterior base of the tentacula ; region of the 

 mouth, the tentacula, and a stripe each side of the neck, leaving a 

 pyramidal dark line between, of a light drab color ; foot oval, bifid, 

 and dilated into wings before, rounded behind, dusky above and 

 pale beneath. Motions very active. 



Found plentifully on sea-weed, and on moist l)anks, about high- 

 water mark, especially on the thread-like plants which grow in 

 ditches and brackish pools about marshes, in company with Litto- 

 rina tenebrosa. 



Whole coast of New England (Stimpson^ ; Halifax ( Willis} ; 

 Green Island (Be//) ; fossil, Montreal {Dawson). 



It is closely allied to several species received from Europe, and 

 perhaps identical with some one of them; as the Liltorina BaWnca, 

 from Copenhagen ; the Turbo ii/vcc, from England ; and the Palu- 

 dina t/iermalis, from France. But, as the shell has been submitted 

 to Mr. Sowerby, and he did not pronounce it a European species, 

 but sent the last-named shell as the nearest allied to it of all the 

 species with which he is acquainted, and as it certainly is not iden- 



