276 MOTIONS OF INSECTS. 
some they have the form as well as the office of legs?. 
Bonnet mentions an apodous larva, that, before it can 
use its mandibles, is obliged to spin, at certain intervals, 
little hillocks or steps of silk; of which it then lays hold 
by them, and so drags itself along. 
Besides their mandibular hooks, some of these grubs 
supply the want of legs by means of claws at their anus. 
Thus that of the flesh-fly, Ray tells us in the place just | 
quoted, pushes itself by the protruded spines of its tail. 
The larva also of a long-legged gnat (Tipula replicata, 
L.), which in that state lives in the water, is furnished 
with these anal claws, which, in conjunction with its an- 
nular tension and relaxation, and the hooks of its mouth, 
assist it in walking over the aquatic plants”. 
A remarkable difference, according to their station, 
obtains in the bots of gad-fiies ; those that are subcutane- 
ous (Cuticole, Clark) having no unguiform mandibles ; 
while those that are gastric (Gastricole, Clark), and 
those that inhabit the maxillary sinuses of animals (Ca- 
vicola, Clark), are furnished with them. In this we 
evidently see Creative Wisdom adapting means to their 
end. For the cuticular bots having no plane surface 
to move upon, and imbibing a liquid food, in them the 
mandibular hooks would be superfiuous. But they are 
furnished with other means by which they can accom- 
plish such motions, and in contrary directions, as are 
necessary to them; the anterior part of each segment 
being beset with numbers of very minute spines, not 
visible except under a strong magnifier, sometimes ar- 
"Vor. I. 2d Ed. 138. De Geer, vi. 76. Reaumur, iv. 376. 
Swamm. Bibl. Nat. Ed, Hill, ii. 46. a. ¢. xxxix. fi 3, A. hh. 
>’ De Geer, vi. 355. 
