868 LITTORINID^. 



that the reason for the female having a larger body is 

 that she requii'cs more space to develope the fry within 

 it than if she had merely to produce eggs. The shells 

 of the fry are not umbilicate. A section of the spire in 

 the adult shows that the apex is solidified, in conse- 

 quence of the first two whorls (which had become too 

 small to contain the upper fold of the liver, and were 

 therefore useless) being filled up with new shelly matter. 

 The shell, when injured, can be repaired to a great 

 extent. A specimen which I picked up in Shetland had 

 been cracked and broken in two, probably by some bird, 

 which may have been interrupted in its meal : the frac- 

 ture appeared to be too extensive to admit of a complete 

 renewal of the severed portion, but it was patched up, 

 so that the remnant of the shell served the purpose of 

 the surviving and lucky periwinkle. 



I consider the present species to have been the Nerita 

 littorea of Fabricius, L. groe7iIandica of Menke and 

 others, and L. sulcata also of the last-named author. 

 L. zonaria and L. rudissima of Bean can hardly be 

 called varieties (much less distinct forms) of this protei- 

 form species. 



4. L. lito'rea"^, Linne. 



Turbo Wforens, Linn. S. N. p. 1232. L. littorea, F. & H. iii. p. 29, 

 pi. Ixxxiii. f. 7, 8, and (animal) pi. G G. f. 3. 



Body sootcolour, or pale-yellowish, marked with close-set 

 transverse stripes of piirphsh-black, and irregularly cross barred 

 with lines of the latter colour : mantle thick, yellowish-white, 

 Hning the inside of the mouth or opening of the shell : head 

 semicircular and projecting: tentacles annulated or streaked 

 across with black ; they are contractile or compressible to such 

 an extent as to be sometimes flattened ; tips blunt : ei/es pro- 



* Livino; on the shore. 



