LITTORINA. 357 



decussation : colour most variable, yellow, brown, red, green, 

 and purple of all shades, diversified by bands, streaks, tessel- 

 lated or reticulated and zigzag markings of every conceivable 

 kind ; the predominant hues are yellow and brown ; it is 

 rarely milk-white : epidermis membranous, yellowish or horn- 

 colour, usually thin : sjm^e very blunt and sometimes flattened: 

 wJiorls 5-6, convex, but somewhat compressed or squeezed 

 together; the last embraces nearly the whole spire: suture 

 narrow although distinct : mouth large, occupying nearly half 

 the lower portion of the shell, sharply angulated below in young 

 specimens : outer lip thick, a little incurved above, and form- 

 ing with the inner lip an acute angle in that part : inner lip 

 thin, spread like glaze over that side of the mouth, and in- 

 dented in the middle : jjillar curved, sloping outwards, white 

 and thick : inside polished, coloured like the outside ; edges 

 often stained with purple : operculum having 4 or 5 whorls, 

 the outermost of which occupies nearly the entire area ; it 

 is marked across with microscopical and close-set curved 

 striae or wrinkles, which are not quite regular, but frequently 

 anastomose or interlace. L. 0-65. B. 0-5. 



Yar. 1. neritiformis. Shell squeezed together at the sides, 

 so as to make it longer and the periphery angulated. L. neri- 

 tiforma, Brown, 111. Conch. G. B, & I. p. 17, pi. x. f. 24. 



Yar. 2. ornata. Smaller and rather more convex, having 

 the spire somewhat more produced, and ornamented with broad 

 reddish-brown bands on a white or yellowish-white ground. 

 L. palliata, F. & H. iii. p. 51, pi. Ixxxiv. f. 8-10. 



Yar. 3. fahalis. Dwarfed or young, inclined to a globular 

 shape. Turbo fabcdis, Turton, in Zool. Journ. ii. p. 366, tab. 

 xiii. f. 10. 



Yar. 4. compacta. Smaller, thick set, and also subglobular. 



Monstr. Scalariform, with a very broad base and a keel en- 

 circling the upper part of each whorl, or having the suture 

 deeply and widely excavated. 



Habitat : Among stones and Fuci on all beaches be- 

 low high-water mark of neap tides. The 1st variety is 

 not uncommon in the west and north of Scotland, and in 

 Shetland; and Captain Brown has given Downpatrick as 

 an Irish locality. The 2nd abounds in the Isle of Wight 



