MOTIONS OF INSECTS. a3 
of no great use to them, and to these last a considerable 
impediment. They are capable of three kinds of mo- 
tion;—they either walk, or jump, or swim. I use 
walking in an improper 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 pre- 
ceed) 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 re- 
semble the ‘zncessus 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 
late discovery,—that some serpents push themselves 
along by the points of their ribs, which Sir E. Home 
has found to be curiously constructed for this purpose,— 
their wonder would haye 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 num- 
bers of larvee, 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 con- 
traction and ‘extension of the segments of their body. 
Had the ancient Egyptians been aware of this, their 
catalogue of insect divinities would have been wofully 
crowded. In this annular motion, the animal alternately 
S a Bncycl, Brit., art. Physiology, 709. 
VOL. ITI. an 
