STATES OF INSECTS. (Larva.) 107 
relative length from that which they subsequently ac- 
quire; and the palpi in the males, which previously to 
the discoveries of Treviranus were regarded as their 
sexual organs, are not yet fully developed*: and a si- 
milar difference takes place in the legs of Phalangia. 
The general form too of the body undergoes slight alter- 
ations, and the colour very considerable ones, with each 
change of the skin—a change to which all these tribes 
are subject. 
The larvee of the three last-mentioned tribes (the 
mites, centipedes, and millepedes) differ from the per- 
fect insect not only in the proportion but also in the 
number of their parts. Leeuwenhoek states (and De 
Geer confirms his assertion, extending it to other species 
of mites>), that the common cheese-mite, which in its 
perfect state has eight legs, when first excluded from the 
ego has but szz, the third pair being wanting®. Some 
however are born with ezght legs, for instance Cheyletus 
eruditus of Schrank, which he saw come from the egg 
itself with that number‘. Others again have never more 
than six legs: this is the case with the genera—Caris, 
Leptus, Atoma, and Ocypetes*. In the centipedes (Scolo- 
pendrid@) and millepedes (Iulid@) differences still more 
remarkable, as I have stated in a former letter, have 
been observed by De Geer; these animals, in their pro- 
gress to the perfect state, not only gain several additional 
pairs of Jegs, but also several additional segments of the 
body. This illustrious Entomologist found that Pollyxe- 
nus lagurus was born a hexapod, with but three segments 
and as many pairs of feet, but successively acquired five 
* De Geer vii. 197. » Tbid. 85. © Epist. \xvii. 1694, 390. 
¢ Enum, Ins. Austr. 5795. © N, Dict. d Hist, Nat. i. 74. 
