Fam. 63.] NATURAL HISTORY SOCIETY. 143 



* Umbilicus none L Littorina. 



* Umbilicus a deep groove 2. Lacuna. 



1. LiTTOKiNA, Fer. The Periwinkles. 

 Shell top-shaped, thick, pointed, few whorled ; aperture round- 

 ed, outer lip sharp ; columella rather flattened, imperforate ; 

 operculum paucispiral. 



1. Littorina rudis^ Don. Shell very variable, heavy to medium, 

 coarse to smooth, subovate, ventricose, with a somewhat pointed 

 spire ; whorls convex, covered with more or less distinct, revolv- 

 ing, elevated lines, 10 or 12 on the body whorl, with the inter- 

 vening spaces finely reticulated. The heavy, coarse shells have 

 the outer lip bevelled within to a sharp edge which is rendered 

 denticulate by the revolving lines. Color yellow, orange, black, 

 brown, green, or reddish, usually uniform, occasionally banded 

 or mottled. Animal with olive-colored head, and an olive line 

 on sides of the foot. L. 14 ; D. 7-10 ; An. 60°-70° ; Wh. 5-6 ; 

 Ap. \. Shell so variable that it has received a score of names. — 

 N. J. and north. Abundant on rocks. 



2. Littorina litorea, L. Solid, not smooth, yet rarely ridged, 

 but more or less covered with elevated, spiral lines ; whorls usu- 

 ally concavely impressed round the upper part; columella 

 broadly callous, slightly arcuated, white. Olive, ash, fulvous, 

 brown, or red, sometimes banded and lined with black ; outer 

 lip joining the body at an acute angle, its edge usually dark. 

 Very variable in size, color, and length of spire. Animal with a 

 general dark color above ; the sole of the foot yellowish-white. 

 L. 20-25; D. 16-20; An. 80°; Wh. 6-7; Ap. J.— New England 

 to Delaware Bay. 



3. Littorina palUata, Say. Shell globular-ovate, thick, smooth 

 and shining, with ver}^ faint revolving lines, and lines of growth ; 

 last whorl very large, the others scarcely rising above it ; suture 

 faintly marked ; aperture nearly circular, the outer lip bevelled 

 within to a sharp edge ; inner lip broadly flattened and white ; 

 color variable, white, yellow, orange, olive, slate, and brown ; usu- 

 alh^ of a single color, often mottled or banded. Animal has the 

 head orange, darker above, and the foot drab or cream-color. L. 

 15; D. 13; An. 95°; Wh. 4; Ap. f-f.— New Jersey and north. 

 Abundant on rocks. 



4. Littorina irrorata, Say. Shell heavy, with numerous, revolv- 



