246 



MOTIONS OF INSECTS, 



be subdivided, as was just observed, into motions whose object 

 is change of place — and sportive motions. 



The locomotions of these animals are walking, running, 

 jumping, climbing, flying, swimming, and burrowing. I 

 begin with the ivalkers. 



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. Hexapods, or those that have 

 only six legs : such are those of every order except the Aptera 

 of Linne, 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 (Araneidce) ; long-legged spiders 

 (Phalangiidce) ; and scorpions (Scorpionidce) : — Poly pods, or 

 those that have fourteen legs, consisting of the wood-lice 

 tribe ( Oniscidce) ; — and Myriapods, or those that have more 

 than fourteen legs — often more than a hundred — composed 

 of the two tribes of centipedes (Scolopendridce) and millepedes 

 (Julidce). The first of these classes may be denominated proper, 

 and the rest 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 AraneidcB, &c. the shank has two), and the foot having 

 from one to above forty. 1 



In walking and running, the hexapods, like the larvae that 

 have perfect legs, move the anterior and posterior leg of one 

 side and the intermediate of the other alternately, as I have 

 often witnessed. De Geer, however, affirms that they 

 advance each pair of legs at the same time 2 ; but this is 

 contrary to fact, and indeed would make their ordinary 

 motions, instead of walking and running, a kind of canter 

 and gallop. Whether those that have more than six feet 



1 The most common number of joints in the tarsus is from two to five ; but 

 the Phalangitis 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 be- 

 longing to the Brachyptera — both Oxytelus Grav., and another genus that I have 

 separated from it ( Carpalimus K. Ms. ), have only two joints in their tarsi. In 

 this tribe, therefore, it can only be used for secondary divisions. — K. 



2 De Geer, iii. 284. 



