STATES OF INSECTS. (Larva.) 137 
Cossus, at least in an American species (Cossus Robinia), 
described by Professor Peck ?, the anal prolegs have the 
claws only on their evterior half. 
4. The remaining description of unguiferous prolegs, 
if they may not rather be deemed a kind of tentacula, 
and perhaps connected with their respiration? ? 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 larva, which from their long re- 
spiratory anal tubes Reaumur denominates “ rat-tailed,” 
that of Helophilus pendulus, there are fourteen of these 
prolegs, affixed by pairs to the ventral segments, the 
twelve posterior ones of which are subconical, and trun- 
cate 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 expan- 
sion, and in shape almost exactly resemble those of a 
mole*. The prolegs of the larve of a kind of gnat 
called by De Geer Tipula amphibia, and of Volucella 
plumata, are nearly of a similar construction, but in the 
last are armed with three claws only 4. Long moveable 
claws also distinguish the singular prolegs before de- 
scribed® of another gnat (Zanypus maculatus). The 
case-worms (Trichoptera) and some others, have two 
prolegs at the anus, each furnished with a single claw '. 
ii. The prolegs deprived of claws are found in the 
* Account of Locust-tree Insects, 69. 
> See Mr. W. S. MacLeay Philos. Mag. N. Ser. n. 9. 178—. 
* Reaum. iv. 443. ¢, xxx. f. 6.11. ¢. xxii. f. 6. 27. 
4 De Geer vi. 383. and 137. ¢. viii. f. 8, 9. 
® See above, Vor. II. p. 278. De Geer ubi supr. 3762 
f Reaum. iy. 184, 4, xv. f. 12. cc. 
