the Carihcean Islands. 171 



lish a correspondence likely to be useful to the interests of science, 

 with the Baron d'Audebard de Ferussac, the author of the most splendid 

 work which has yet appeared on the Mollusca. 



The difficulty of preventing these animals from shrinking and with- 

 drawing their organs when thrown into spirit, is scarcely removed by 

 quickly dashing boiling water over the specimens ; and in the testaceous 

 genera the process is not sufficiently sudden to secure the object aimed 

 at. Perhaps some Zoologist residing on the coast, Avho has a good elec- 

 trical machine, will make some experiments with the view of killing the 

 animals while in their natural attitude of creeping. A wire might be 

 made fast round the shells, and the favourable moment easily seized for 

 communicating the shock. The spire should be cracked or perforated to 

 prevent putrefaction before the animal is preserved in spirit. ^ 



In the second volume of this Journal, page 497, Mr. Brayley has 

 given an ingenious paper on those organs of the Helicidce, usually re- 

 garded as their eyes, which is particularly valuable from its presenting at 

 one view all that has been said on the subject by preceding writers. 



Mr. Bauer's microscopical examination of the tentacula of the garden 

 snail reached me after the note quoted by Mr. Brayley had been \vritten, 

 but has done nothing to remove my opinion that these spots are really 

 ill developed eyes, not indeed in the Helicidce capable of distinguishing 

 objects, but certainly susceptible of the impressions of light. In the 

 Helicidce the superior tentacula are usually carried erect, and the inferior 

 ones writh the lobes of the cheeks are principally used as tactors. In 

 Helicina, which has only two tentacula, they are in constant motion, 

 touching the path in which it is gliding ; while the scarcely prominent 

 ocular points, seated at their base, can in no degree, nor under any cir- 

 cumstances, be employed to assist the sense of touch. 



As far as the Helicidce are concerned, the latter part of the note added 

 at page 507, admits all I would contend for. In Helicina, &c., the eyes 

 are perhaps somewhat more fully developed, but from the minuteness of 

 these animals, we shall require a Bauer for their examination. 



Mr. Brayley errs in supposing, page 508, that I alluded to the Cepha- 

 lopoda, as to which no doul)t could exist. Had he an opportunity of 



M 2 



