MOTIONS OF INSECTS. 307 
or those that have only szv legs: such are those of every 
order except the Aptera 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 (Aca- 
ride); spiders (Araneide); long-legged spiders (Pha- 
langide); and scorpions (Scorpionide):—Polypods, or 
those that have fourteen legs, consisting of the woodlouse 
tribe (Oniscide);—and Myriapods, or those that have 
more than fourteen legs—often more than a hundred— 
composed of the two tribes of centipedes (Scolopendride) 
and millepedes (Julide). The first of these classes may 
be denominated proper, and the rest zmproper 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 Araneid@e &c. 
the shank has two), and the foot having from one to 
above forty *. 
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 alter- 
nately, as I have often witnessed. De Geer, however, 
affirms that they advance each pair of legs at the same 
2 The most common number of joints in the tarsus is from two to 
five; but the Phalangidz 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 Staphy- 
linide—both Oxytelus, Grav., and another genus that I have sepa- 
rated 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. 
KD 
