432 MOTIONS OF INSECTS. 
parable provision made in the feet of such as walk or hang upon smooth 
surfaces ; the great strength and spring in the legs of such as leap ; the 
strong-made feet and talons of such as dig; and, to name no more, the 
admirable faculty of such as cannot fly, to convey themselves with speed 
and safety, by the help of their webs, or some other artifice, to make their 
bodies lighter than the air.” ? 
Since the motions, and instruments of motion, of insects are usually 
very different in their preparatory states, from what they are in the imago 
or perfect state, I shall therefore consider them separately, and divide my 
subject into — motions of larva, motions of pupa, and motions of perfect 
insects. 
I. Amongst Jarve there are two classes of movers; Apodous larvae, or 
those that move without legs, and Pedate larve, or those that move by 
means of legs. I must here observe, that by the term /egs, which I use 
strictly, I mean only jointed organs, that have free motion, and can walk 
or step alternately; not those spurious legs without joints, that have no 
free motion, and cannot walk or take alternate steps ; such as support the 
middle and anus of the larvae of most Lepidoptera and saw-flies (Serrifera). 
Apodous lavyee seldom have occasion to take long journeys ; and many 
of them, except when about to assume the pupa, only want to change 
their place or posture, and to follow their food in the substance, whether 
animal or vegetable, to which, when included in the egg, the parent insect 
committed them. Legs, therefore, would be of no great use to them, and 
to these last a considerable impediment. They are capable of three kinds 
of motion; they either walk, or jump, or swim. I use walking in an im- 
proper sense, for want of a better term equally comprehensive : for some 
may be said to move by gliding, and others (I mean those that, fixing the 
head to any point, bring the tail up to it, and so proceed) by stepping. 
The motion of serpents was ascribed by some of the ancients (who were 
unable to conceive that it could be effected naturally, unless by the aid of 
legs, wings, or fins) to a preternatural cause. It was supposed to resemble 
the “incessus deorum,’ and procured to these animals, amongst other 
causes, one of the highest and most honourable ranks in the emblematical 
class of their false divinities? Had they known Sir Joseph Banks's dis- 
covery, that some serpents push themselves along by the points of their 
ribs, which Sir E. Home found to be curiously constructed for this pur- 
pose, their wonder would have been diminished, and their serpent gods 
undeified. But though serpents can no longer make good their claim to 
motion more deorum, some insects may take their places; for there are 
numbers of larvae that, having neither legs, nor ribs, nor any other points 
by which they can push themselves forward on a plane, glide along by the 
alternate contraction and extension of the segments of their body. Had 
the ancient Egyptians been aware of this, their catalogue of insect divinities 
would haye been wofully crowded. In this annular motion, the animal 
alternately supports each segment of the body upon the plane of position, 
which it is enabled to do by the little bundles of muscles attached to the 
skin, that take their origin within the body.® 
1 Physico-Theol, Ed. 13. 866. 
2 Eneycl, Brit., art. Physiology, 709. 
5 Cuvier, Anat. Comp. 1. 42). 
