78 DR. T. ALCOCK ON THE 



pura I have examined agree in structure and type of ribbon 

 with Murex ; but in their arrangement Purpura is placed 

 with Buccinwn, from which it is anatomically quite distinct. 

 I say^ then^ that whether or not Fusus and Buccinum may 

 be sufficiently different in their operculum and other ex- 

 ternal characters to require their being placed in distinct 

 families_, it is evidently wrong to unite Fusus with Murex, 

 and Purpura with Buccinum. 



In my drawings^ the character of the teeth of the Muri- 

 cidce is shown by Purpura biserialis and Cerastoma Nuttalli, 

 which may be compared with the teeth of Buccinum, also 

 represented. Nassa, I may remark^ agrees in its type of 

 teeth with Buccinum and Fusus. 



This closes my present communication on the tongues of 

 Mollusca; but as some members may possibly feel in- 

 clined to enter upon the inquiry themselves_, I think it will 

 not be amiss to add a few remarks on the manner in which 

 they are to be obtained. 



Firsts as to the kinds best worth the trouble of prepara- 

 tion. Whelks_, Limpets, and Trochuses should be taken 

 first. Land and freshwater Snails can scarcely be recom- 

 mended, except as a special study, their tongues being 

 rather more difficult to find, and the teeth so small that 

 they require a high power to show them properly. It 

 would appear from Spallanzani's description of the ana- 

 tomy of the head of the Snail, that even he did not make 

 out this part, although, in his curious observations on the 

 reproduction of lost parts, he must have carefully dissected 

 more Snails than any other man. 



As to preserving the animals till wanted, they should 

 simply be dropped alive into glycerine or alcohol. Glycerine 

 is perhaps best, where only the tongues are wanted ; but 

 it leaves the animals very soft, and as it does not harden 

 their mucus at all, they are very slippery and difficult to 

 work upon when so preserved. 



