FAMILY TURBINID^ LITTORINA. 105 



LiTTORINA TENEBROSA. 



- • . PLATE VI. FIG lOG. 



. (STATE COLLECTION.) ' " .V 



Turbo tenebrosus. Montagu, Test. Brit. 



T. vestitus. Say, Jour. Acad. Nat. Sc. Rcssel, Essex Journ. Vol. 1, p. 72. 



Littorina tenebrosa. Gould, Jnvertebrata of Mass. p. 259, fig. 1G6. 



Description. Shell small, conic, not as stout as the preceding. Spire elevated and pointed, 

 as long as the aperture. Whorls five to six, rounded, with faint revolving lines. Suture 

 deeply impressed : lip thin, acute. 



Color, variable : according to Mr. Say, usually invested witii a soiled greenish white pig- 

 ment, beneath which it is sometimes reticulated with abbreviate yellow lines on a brown or 

 dusky ground. Animal with a dark olive head, and an olive stripe on the tentacles from the 

 eye : sides of the foot lined with the same. 



Length, 0"5. Diameter, 0'3. 



Scarcely any species varies more in its external markings, and the specimen figured is only 

 one of numerous varieties. They are brown, immaculate, black, green, sometimes reddish, 

 with pale revolving lines, and occasionally as represented in the figure. Mr. Sowerby, 

 after a careful comparison of specimens, believes that vestitus and ohligatus are both identical 

 with the tenebrosa of Montagu. I coincide with Dr. Gould in referring only to this latter 

 species, the vestitus of Say. 



Littorina neritoides. 



PLiTE VI. FIG. 109. a. b. Youno ; FIG. 110. A. B. Adolt.— PL.\TE VI. FIG. 111. a. b. Adult. T neritoides of Europe. 



T. neritoides. LiNN. Syst. Nat. 1232. 



Littorina palliata, Gould, Invertebrata of Mass. p. 2G0 (exd. syn.). 



Description. Shell small, very thick, smooth in the adult ; with minute revolving and vertical 

 lines in the young. Whorls four ; the spire is flattened, and (except in very young shells) 

 scarcely rises above the body. Suture moderately distinct in the young, but very faintly 

 marked in the adult. Aperture nearly circular, or slightly oval ; the lip acute, entire, bevelled 

 on its inner margin, which is continuous with the curve of the pillar-lip in the adult. Opercle 

 corneous, smooth, subspiral. 



Color, variable, usually uniform sulphur-yellow, as represented in figs. 109 and 110 ; the 

 young being of a dark amber brown: often whitish, greenish or orange, and occasionally 

 striped. " Animal : head orange, darker above ; the foot drab or cream-color" (Gould). 



Length, 0*4- 0-6. Diameter of adult, 0-7. 

 Fauna — Part 6. 14 



