LITTORINA. 369 



minent, on short, thick, and somewhat angular stalks : pupils 

 black, within yellowish or dull pearly irides : foot large, double- 

 edged in front, stri2)ed like the rest of the body ; sole light 

 yellowish-brown or j^ale fleshcolour, divided lengthwise in the 

 middle by a transparent line. 



Shell forming a cone of moderate height, thick, opaque, 

 and mostly of a dull hue : sculpture, numerous fine spiral flat- 

 tened ridges, crossed obliquely by slight irregular striae or 

 lines of growth ; the surface is also covered with close-set 

 minute spiral wrinkles, as in L. rudis, but these are in the 

 present species more strongly marked, and are slightly decus- 

 sated or even punctured by the intersection of the longitudinal 

 striae: colour not so various as in the last species, commonly bis- 

 tre, yellowish with dark-brown zones or rings, or greyish-yel- 

 low, occasionally reddish-orange, and very rarely white : epider- 

 mis light yellowish-bro^vn, usually obscure or not visible, some- 

 times thick and velvety: spire sharp -pointed: ivhorls 7-8, more 

 convex in female than in male individuals, compressed upwards 

 towards the suture, so that the top of each lower whorl over- 

 laps the periphery of the one above it; the proportional 

 difference between the size of the last whorl in the two 

 sexes is not so great as in L. rudis, although in the present 

 species each sex is also distinguishable by its shape : suture 

 slight and indistinct : moutli equal to nearly one-third of the 

 lower portion of the shell in females, but rather smaller in 

 males, narrowly angulated above, and considerably expanded 

 as well as bluntly angulated below: outer lip rather thin, 

 somewhat reflected in full-grown males, flexuous, but not in- 

 curved, towards the pillar: inner Up forming a white glaze on 

 the upper part of the mouth : pillar short but thick ; it is 

 always white, and shelves inwards : inside or throat usually 

 chocolate -colour, now and then of a pale hue or whitish ; 

 margin exhibiting the coloured bands when present ; inter- 

 mediate space white : opercidum dark-horncolour, having the 

 same number of volutions and lineated in the same manner as 

 L. rudis; the under side is likewise similar. L. l*2o. B. 1. 



Yar. 1. paupercvla. Somewhat dwarfed, with the whorls 

 more convex, of a dusky hue. 



Yar. 2. brevicula. Smaller and ventricose, with a short 

 spii'e. 



Yar. 3. turrita. Spire turreted, the whorls being divided 

 by a deep and channelled suture. 



R 5 



