88 SYSTEMATIC ARRANGEMENT 



3. L. canadensis, t. 125. f. 10. 



4. L. serialis, t. 127 a- f. 3. 



5. L. patula, Forbes #• Hartley, B. M. t. G.G. f. 2. 



6. L. Gaudichaudi, t. 127 a. f. 1. 



7. L. peruviana, t. 123. f. 4. 



8. L. Araucana, t. 123. f. 1. 



9. L. flava, t. 123. f. 2. 



10. L. diemensis, t. 51. f. 3. 



11. L. luteola, t. 51. f. 2. 



12. L. scabra, t. 51. f. 1. 



13. L. pyramidalis, t. 51. f. 6. 



14. L. miliaris, t. 123. f. 5. 



15. L. punctata, t. 51. f. 5, with a produced siphon? like a Buc- 



cinum ! 



The tentacles subulate, rather distant. The eyes rather promi- 

 nent, on the outer base of the tentacles. Operculum horny, ovate, 

 spiral, of a few very rapidly enlarging whorls. They inhabit the 

 sea-coast between high and low water mark, where they are often 

 left dry for many hours by the tide ; and sometimes they crawl so 

 high up the rock as only to be wetted by the spray. The pectina- 

 tions of the branchial plume of nearly all the Littorince vary from 

 forty-five to sixty ; thin, long, slender, and close-set. 



The branchial plume of Littorina littoralis is single, on the left 

 side, with thirty-five to forty or more very fine, close-set pectina- 

 tions ; the neck is simple, without lobes. — Clark, 347. 



The anterior folded jaws of L. littoralis are supported by the 

 usual corneous plates. — Clark, 347. 



The buccal mass of L. neritoides is supported by two thin, brown, 

 corneous plates, from whence a very long, white, spiny tongue pro- 

 ceeds to the stomach, and there lies coiled as in L. littorea. — Clark. 



Central tooth of Littorina littorea (fig. 49) subquadrate, convex 

 above ; cutting edge narrow, cordate-lobed in the middle, on both 



Kg. 49. — Teeth of Littorina littorea. 



sides obtusely denticulate. Lateral teeth somewhat similar, thick, the 

 tip unequally dentate-lobed, the first on the outside curved and pro- 

 duced. 



In walking, Littorina littorea alternately advances first one and 

 then the other side of the foot. 



