2. The larvæ of many minute moths, particularly of the Fabrician genera _Tortrix_ and _Tinea_--those which live in convoluted leaves, the interior of fruits, &c., as well as the _Cossus_, and some other large moths,--have their prolegs of a form not very unlike those of the preceding class, but shorter, and without any terminal expansion; the apex, moreover, is wholly, instead of half, surrounded with claws[300]; the additional provision of which, together with a centrical kind of nipple capable of being protruded or retracted, in some measure, though imperfectly, supplies the place of the more flexible plate-like expansion present in the first class.
3. The third class is composed of a very few _Lepidopterous_ larvæ which have their prolegs very thick and conical at the base, but afterwards remarkably slender, long, and cylindrical, so as exactly to assume the shape of a wooden leg[301]. These, as in the first class, are expanded at the end into a flat plate: but this is wholly circular, is surrounded with claws, and has also in the middle a retractile nipple, as in the preceding class. In _Cossus_, at least in an American species (_Cossus Robiniæ_), described by Professor Peck[302], the anal prolegs have the claws only on their _exterior_ half.
4. The remaining description of unguiferous prolegs, if they may not rather be deemed a kind of tentacula, are those of certain _Diptera_, provided with no true legs; which differ from the three preceding classes, either in their shape, or the arrangement of their claws. In one kind of those remarkable larvæ, which from their long respiratory anal tubes Reaumur denominates "_rat-tailed_," that of _Elophilus pendulus_, there are fourteen of these prolegs, affixed by pairs to the ventral segments, the twelve posterior ones of which are subconical, and truncate at the apex, which is surrounded with two circles of very minute claws, those of the inner being much more numerous and shorter than those of the exterior circle; while the anterior pair terminate in a flat expansion, and in shape almost exactly resemble those of a mole[303]. The prolegs of the larvæ of a kind of gnat called by De Geer _Tipula amphibia_, and of _Syrphus mystaceus_ F., (_Musca plumata_ De Geer,) are nearly of a similar construction, but in the last are armed with three claws only[304]. Long moveable claws also distinguish the singular prolegs before described[305] of another gnat (_Tanypus maculatus_ Meig., _Tipula_ De Geer). The case-worms (_Trichoptera_ K.) and some others, have two prolegs at the anus, each furnished with a single claw[306].