“But the peculiarity of the toothed membrane, which makes its name of ‘_ribbon_’ so appropriate, is, that there is always a considerable length of it behind the mouth, perfectly formed, and ready to come forward and supply the place of that at the front, which is continually wearing away by use. “In the limpet this reserve-ribbon is of great length, being nearly twice as long as the body, and the whole of it is exposed to view on simply removing the foot of the animal; nothing, then, can be easier than to extract the tongue of the common limpet. But, unfortunately, what you find in one kind of mollusc is not at all what you find in another. In the Acmæas, for instance, which are very closely related to the limpets, and have shells which cannot be distinguished, the reserve portion of the ribbon has to be dug out from the substance of the liver, in which it is imbedded, that organ being, as it were, stitched completely through by a long loop of it.... It might be thought a comfortable reflection that, at all events, one end of the ribbon can always be found in the mouth; but in many cases this is about the worst place to look for it. Perhaps it may appear strange that in some of the smaller species, with a retractile trunk, a beginner may very likely fail altogether in his attempt to find the mouth; if, however, the skin of the back is removed, commencing just behind the tentacles, there will be very little difficulty in making out the trunk, which either contains the whole of the ribbon, as in the whelk, or the front part of it, as in _Purpura_ and _Murex_, where a free coil is also seen to hang from its hinder extremity.... In the periwinkles the same plan of proceeding, by at once opening the back of the animal, is best; and on doing so, the long ribbon, coiled up like a watch-spring, cannot fail to be found. “In the Trochuses, and indeed in all the _Scutibranchiata_, one point of the scissors should be introduced into the mouth of the animal, and an incision made directly backwards in the middle line above to some distance behind the tentacles; the tongue is then immediately brought into view, lying along the floor of the mouth.” Dr. Alcock’s method of dissection will be found to differ in some degree from the general rules before given; and when the tongue is dissected out he washes it for one hour (shaking it now and then) in a weak solution of potash. After cleaning thoroughly in water, it must be mounted by one of the methods before mentioned. Amongst insects, especially the grasshopper tribe, are found many which possess a gizzard, armed with strong teeth, somewhat similar to those of the molluscs. It requires great nicety of manipulation to obtain these for the microscope; but it would be useless to attempt any description of the process here, as the strident can only be successful by experience in dissecting objects less difficult to manage, and by using the most delicate instruments.