298 LITTORINIDJ;. 



Rissoa minuta. 



Fig. 171. 



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

 vex ; suture distinct. 



Turl)o iitinutus, Totten, Sillim. Journ. xxvi. 369, fi<^. 7. 



Cimjula minuta, Gould, Inv. Isted. 265, lig. 171. — De Kay, N. Y. Moll. 110, pi. 4, fig. 117. 



liissoa minuta, Stimpson, Check Lists, 4. 



Paludina stagnalis {forma ventr.), Middendorf, Rcise, 34. 



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

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

 coated with a dark green pigment, or some minute vegeta- 

 Fig. 508. ^Yq ; Avhorls fivc, couvcx, faintly wrinkled by the lines of 

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

 the lowest less than two thirds the wdiolc length of the 

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

 „ . , near it ; aperture 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 specimens, 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 black-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 ( Stiinpson') ; Halifax ( Willis') ; 

 Green Island (Bell) ; fossil, Montreal {Dawson). 



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

 perhaps identical with some one of them; as the Liltorina Balt/tica, 

 from Copenhagen ; the Turbo iilca, from England ; and the Palu- 

 dina thcrmalis, 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 ideii- 



