ON THE LAND MOLLTTSCA. 
25 
coloured cotton-wool, which shows them off better than a white 
ground. 
The linear arrangement and naming of the species is the next 
thing to consider, and I would advise the adoption of the classifica¬ 
tion and nomenclature followed by our greatest authority on the 
Mollusca, Dr. Gwyn Jeffreys, F.R.S., in his ‘ British Conchology ’ 
(vol. i, 1862, and vol. v, 1869), with such modifications as recent 
research and the discovery of new species and varieties necessitate. 
Dimmer, in his ‘Land and Freshwater Shells’ (1880), follows Dr. 
Jeffreys, and the same general classification and sequence of species 
is followed in the Conchological Society’s 1 Exchange-list of .British 
Land and Freshwater Mollusca,’ published by Messrs. Taylor Bros., 
Leeds, which is a very useful list for reference ; a neatly-printed 
1 Label-list ’ is also published by the same firm. These lists 
enumerate all the species and varieties of the British Land and 
Fresh-water Mollusca known up to the date of their publication 
a few months ago. On the labels accompanying the specimens 
should of course be recorded the locality in which they were found, 
and it would he advisable to add the habitat or the food-plant. A 
register may also be kept in which further particulars may be 
entered. 
There are many interesting points in the morphology, anatomy, 
and physiology of our land Mollusca which there is not time even 
to allude to. Much might be said about their great tendency to 
variation, frequent monstrosities, and the variation in band-markings 
of some species. Their lingual membrane is a wonderful organ, 
being studded with thousands of minute teeth in rows which they 
push forward from behind as the first rows become worn, and there 
is a definite formula for each species, many of which can be identi¬ 
fied from a microscopical examination of their jaw. Although 
their bodies seem to be little more than a mass of jelly almost 
destitute of muscles and with. a very simple organisation, such is 
not really the case, for their organisation is complex and their 
muscular strength enormous. Their method of reproduction is 
very peculiar, and their manner of making love to each other most' 
singular, for they appear then to be engaged in a pitched battle 
with weapons consisting of calcareous spicules called “ love-darts ” 
which they endeavour to strike into any exposed part of each 
other’s bodies. 
Lastly, I may mention that their organs of sense are those of 
touch, taste, smell, vision, and hearing, their sense of taste and of 
smell appearing to be very slight, and their sense of touch and 
of vision well developed. Their inferior tentacles are their most 
sensitive tactile organs, and their eyes, with a few exceptions, are 
situated at the extremities of their superior tentacles. As they 
have a heart, consisting of a single auricle, a well-developed system 
of nervous ganglia, and a large ganglionic mass with which the 
nerves of their various senses communicate, therefore presumably 
forming a sentient brain, they probably feel pain and pleasure as 
we do, though in a less degree. 
