448 MOTIONS OF INSECTS. 
(vibrans) from the constant vibration which, when reposing, it imparts to 
its wings. This motion, also, I have reason to think, assists its respira. 
tion. Some insects when awake are very active with their antenna, 
though their bodies are at rest. I remember one evening attending for 
some time to the proceedings of one of those caseworm-flies (Leptocerus), 
that are remarkable, like certain moths, for their long antenna. It was 
perched upon a blade of grass, and kept moving these organs, which were 
twice as long as itself, in all directions, as if by means of them it was 
exploring every thing that occurred in its vicinity. Many Tipule, and 
likewise some mites (Acarus vibrans and Gamasus motatorius), distinguished 
by long anterior legs, from this cireumstance denominated pedes motatorii 
by Linné, holding them up in the air impart to them a vibratory motion, 
resembling that of the antenna of some insects.! I scarcely need mention, 
what must often have attracted your attention, the actions of flies when 
they clean themselves ; how busily they rub and wipe their head and 
thorax with their fore legs, and their wings and abdomen with their hind 
ones. Perhaps you are not equally aware of the use to which the rove- 
beetles (Staphylinus L.) put their long abdomen. They turn it over their 
back not only to put themselves in a threatening attitude, as I lately re- 
lated, but also to fold up their wings with it, and pack them under their 
short elytra. 
With respect to the motions of insects in action, they may be subdivided, 
as was just observed, into motions whose object is change of place — and 
sportive motions. 
The /ocomotions of these animals are walking, running, jumping, climbing, 
flying, swimming, and burrowing. I begin with the walkers, 
The mode of their walking depends upon the number and kind of their 
legs. With regard to these, insects may be divided into four classes ; viz. 
Hewxapods, or those that have only siv legs : such are those of every order 
except the Apfera of Linné, of which only three or four genera belong to 
this class ;— Octopods, or those that have eight legs, including the tribes of 
mites (Acarina) ; spiders (Araneid@) ; long-legged spiders (Phalangida) ; 
and scorpions (Scorpionide) : — Polypods, or those that have fourteen legs, 
consisting of the wood-lice tribe (Oniscide) ; — and Myriapods, or those 
that have more than fourteen legs —often more than a hundred —com- 
posed of the two tribes of centipedes (Scolopendride) and millepedes 
(Julidz). The first of these classes may be denominated proper, and the 
Test improper insects. The legs of all seem to consist of the same general 
parts ; the hip, trochanter, thigh, shank, and foot; the four first being 
usually without joints (though in the Araneide, &c. the shank has two), 
and the foot having from one to above forty,” 
1 De Geer, vi. 335. 
® The most common number of joints in the tarsus is from two to five; but the 
Phalangide have sometimes more than forty. In these, under a lens, this part 
looks like a jointed antenna. 
Geoffroy, and after him most modern entomologists, has taken the primary 
divisions of the Coleoptera order from the number of joints in the tarsus; but this, 
although perhaps in the majority of cases it may afford a natural division, will not 
universally. For—not to mention the instance of Pselaphus, clearly belonging to 
the Brachyptera— both Oxytelus Gray., and another genus that I have separated 
from it (Carpalimus K. Ms.), have oniy two joints in their tarsi. In this tribe, 
therefore, it can only be used for secondary divisions —K, 
