MOLLUSCA. 
77 
Trochus cinerarius , 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. Littorinid®, 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 laminarian 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 puteolus , 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. 351, 
v. pi. 64. f. 5 & 5 a. 
On the West Sands after storms, and from the laminarian 
region. 
Genus 2. Littorina, Fdrussac. 
Littorina obtusata, 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 b. 
Abundant on the rocks near high-water mark. 
