104 NEW-YORK FAUNA — MOLLUSCA. 



GENUS LITTORINA. Ferussac. 



Animal with slender elongated tentacles. Mouth only with a lingual band. Foot oblong, 

 with a marginal furrow in front. Organs of generation in both sexes on the right side, at 

 the entrance to the branchial cavity, quite near the vent. Marine. Shell, thick, globular, 

 conic or subturreted ; no umbilicus. Spire of a few rounded whorls. Aperture rounded, 

 large, entire ; outer lip sharp, not continuous behind. Opercle horny, spiral. 



LiTTORINA RUDIS. 



PLATE V. FIG. 103. 



(STATE COLLECTION.) 



Turbo rtidis. MoNTiGH, Test. Brit. Maton and R.tcKETT, Lin. Trans. Vol. 8, p. 150, pi. 4, figs. 12, 13. 

 T. obligalus. Sav, Jour. Acad. Nat. Sciences, Vol. 2, p. 241. Rdssel, Ess. Jour. Vol. 1, p. 72. 

 Littorina rudia. Gould, Invertebrata of Mass. p. 257, fig. 165. 



Description. Shell very strong and coarse, subovate, ventricose. Whorls five to six, con- 

 vex, tapering rapidly to a little elevated spire, and covered with revolving elevated lines and 

 grooves. Body-whorl with 10 - 12 revolving costae, the intervening spaces finely reticulated ; 

 lip plaited by the termination of the costas ; about four of these on the next whorl, and obso- 

 lete above ; base of the lip broadly bevelled ; pillar-margin also broadly flattened. Aperture 

 regularly oval. 



Color. Obscurely brownish : " sometimes orange or olive, occasionally banded with white" 

 (Gould). 



Length, 0'5; of aperture, 0'3. 



A very common little shell on the shores of Long island. From the description alone, I 

 should have considered this as distinct from the rudis, which, according to Maton and Rackett, 

 have the " anfractus interdum leviter striati ;" whereas all of ours are invariably strongly cos- 

 tate. It agrees, however, entirely with a specimen from the North Sea, in Dr. Jay's Cabinet, 

 obtained from the collection of M. Bosc, and labelled " T. rudis, Montagu." 



