PROCEEDINGS OE SOCIETIES. 
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much value in assisting the definition of species, having little external 
to indicate their difference, the dentition of the mollusca occupied a 
subordinate place in their classification. At the same time it was so 
characteristic, that any definition of species must be held to be imper- 
fect without a figure or formula expressing the arrangement of the 
teeth. Instead of making excerpts from hooks, or merely quoting the 
systematic classification of lingual membranes which had been adopted, 
he would mention some books in the library containing the best in- 
formation on the subject: — ‘Microscopical Journal,’ vol. i., p. 170, 
1853, “ Teeth and Tongues of Mollusca,” by Dr. J. E. Gray ; 
‘ Intellectual Observer,’ vol. v., p. 67, 1864, “ Dentition of British 
Mollusca,” by Eev. G. Eowe ; ‘ Transactions of Eoyal Microscopical 
Society,’ July and October, 1868, “ The Lingual Membrane in Mol- 
lusca, and its Value in Classification,” by Mr. Jabez Hogg. 
He strongly advised dissection as the means of obtaining the 
palates, as the experience so gained would be valuable in other inves- 
tigations ; but there was a shorter method, which he had been obliged 
to adopt with such small animals as Balea fragilis (about -J.tli of an 
inch long), or with larger, when many had to be prepared. It was 
simply to cut off the head, or even to take the entire animal, and boil 
it in liquor potassce, when all the soft parts would readily dissolve 
away, leaving the palate, easily to be recognized by its brilliant teeth, 
separate and entire, and requiring only to be well shaken with water 
in a test-tube to free it from extraneous matter. After well washing, 
the palate should be placed in diluted glycerine before mounting in 
glycerine jelly, the best medium for the purpose. He had brought 
down a good series of palates for examination, and would dissect for 
practical demonstration the palates of such mollusks as he had been 
able to obtain. 
Mr. Wonfor, while thanking Mr. Hennah for his paper, was glad he 
intended giving practical instruction in dissection, for he was indebted 
to him for a valuable lesson in palate dissection some years ago ; in 
fact, a common whelk, dissected on that occasion, and which he had 
brought with him, made for Darwin, as one tooth in each row had a 
double instead of a single crown. Some eight years ago he communi- 
cated Mr. Hennali’s plan of boiling in potash to the 1 Intellectual 
Observer,’ giving him credit for the simple plan of readily obtaining 
palates ; and was amused, some five years afterwards, to see it quoted 
from an American journal as a novel American idea. He mentioned 
this, for whatever credit was due for the suggestion belonged to 
Mr. Hennah. 
The meeting then became a conversazione, when Messrs. Hennah, 
Glaisyer, and Wonfor exhibited numerous palates, including those of 
the whelk, limpet, periwinkle, snail, black slug, a vegetable feeder, 
testacella, a carnivorous slug, trockus, haliotis, cuttle-fish, aplysia, 
coris, clausilia, Balea fragilis, Cyclostoma elegans, &c. 
During the evening Mr. Hennah gave practical instruction, by 
dissecting out the palates of snails, whelks, and periwinkles. 
