MOTIONS OF INSECTS. 295 
legs as they use in walking, or by strokes, as in swim- 
ming; others for this purpose employ certain lamin, 
which terminate their tails, as oars; others again swim 
like fish, with an equable motion; some move by the 
force of the water which they spirt from their anus; 
others. again swim about in cases, or crawl over the 
submerged bottom; and others walk even on the surface 
of the water. I shall not now enlarge on all these kinds of 
water-motion, since many will come under consideration 
hereafter. 
There are two descriptions of larvae of Hydrophilz, one 
furnished with swimmers or anal appendages, by means 
of which they are enabled to swim; the other have them 
not, and hence are not able to rise from the bottom*. The 
larvee of Dytisci, by means of these natatory organs, will 
swim, though slowly, and every now and then rise to the 
surface for the sake of respiration. ‘Those of Ephemera, 
when they swim, apply their legs to the body, and swim 
with the swiftness and motions of fish’. Those of the 
true may-fly (Semblis lutaria, F.), on the contrary, use 
their legs in swimming, and at the same time, by alternate 
inflexions, give to their bodies the undulations of ser- 
pents®. But the larvee of certain dragon-flies (Aeshna 
and Libellula, F.) will afford you the most amusement by 
their motions. These larvee commonly swim very little, 
being generally found walking at the botton on aquatic 
plants: when necessary, however, they can swim well, 
though in a singular manner. If you see one swim- 
ming, you will find that the body is pushed forward by 
@ Miger, Ann. du Mus, xiv. 441. b De Geer, ii. 621. 
© Tbid. 725— 
