MOLLUSCA. 77 



Trochiis cmerarius, L. Op. cit. iii. p. 309, v. pi. 62. f. 3. 



In great abundance on stones and rocks between and beyond 

 tide-marks. 



Trochus zizyphinus, L. Op. cit. iii. p. 330, v. pi. 63. f. 6. 

 Not uncommon in deep water and on the beach after storms ; 

 rarely met with at extreme low water at the East Rocks. 

 Var. Lyonsii is occasionally seen. 



Fam. 9. Littormidae, Gray. 

 Genus 1. Lacuna, Turton. 

 Lacuna crassior, Mont. Op. cit. iii. p. 344, v. pi. 64. f. 2. 

 From tangle-roots and in old shells in the lamiuarian region, 

 and from deep water ; not rare. 



Lacuna divaricata, Fab. Op. cit. iii. p. 346, v. pi. 64. f. 3. 

 On Fuci and laminarian blades at and beyond low-water 

 mark. The colourless variety is not uncommon ; and the same 

 may be said of var. quadrifasciata. 



Lacuna, puteolm, Turton. Op. cit. iii. p. 348, v. pi. 64. f. 4. 



With the former at low-water mark ; less common than the 

 foregoing. 



Lacuna pallidula, Da Costa. Op. cit. iii. p. 3.51 

 V. pi. 64. f. 5&5a. ' 



On the West Sands after storms, and from the laminarian 

 region. 



Genus 2. Littorina, F^russac. 

 Littwina obtmata, L. Op. cit. iii. p. 356, v. pi. 65. f. 1 & 1 a. 

 Very common (with varieties) on stones and rocks be- 

 tween tide-marks. 



Littorina rudis^ Maton. Op. cit. iii. p. 364 v pi 65 

 f. 3, 3 a, & 3 J. ' 



Abundant on the rocks near high-water mark. 



