MOTIONS OF INSECTS. 283 
to look like one leg, are placed on the eighth, ninth, and 
tenth. When the animal moves, the body continues 
bent, and the sixth segment, which is without feet and 
forms the summit of the curve, goes first?. De Geer 
named the fly it produces Tzpula amphibia: it seems 
not clear, from his figure, to which of the modern gene- 
ra of the Tipulide it belongs. 
I come now to the jumping apodes, and one of this 
description will immediately occur to your recollection, 
—that I mean which revels in our richest cheeses, and 
produces a little black shining fly (Tephritis putris, ¥.). 
These maggots have long been celebrated for their sal- 
tatorious powers. They effect their tremendous leaps 
—laugh not at the term, for they are truly so when com- 
pared with what human force and agility can accom- 
plish—in nearly the same manner as salmon are stated 
to do when they wish to pass over a cataract, by taking 
their tail in their mouth, and letting it go suddenly. 
When it prepares to leap, our larva first erects itself 
upon its anus, and then, bending itself into a circle by 
bringing its head to its tail, it pushes forth its unguiform 
mandibles, and fixes them in two cavities in its anal tu- 
bercles. All being thus prepared, it next contracts its 
body into an oblong, so that the two halves are parallel 
to each other. This done, it lets go its hold with so 
violent a jerk that the sound produced by its mandibles 
may be readily heard, and the leap takes place. Swam- 
merdam saw one, whose length did not exceed the fourth 
part of an inch, jump in this manner out of a box six 
inches deep; which is as if a man six feet high should 
2 De Geer, vi. 380—2¢. xxiv. f. 1-9. 
