STATES OF INSECTS. 107 



Thus the larvae of spiders have their legs of a different 

 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 a : 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 larvae 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. Leeuwenhoeck states (and De 

 Geer confirms his assertion, extending it to other species 

 of mites b ), that the common cheese-mite, which in its 

 perfect state has eight legs, when first excluded from the 

 egg has but six, the third pair being wanting . Some 

 however are born with eight legs, for instance A. eruditus 

 of Schrank, which he saw come from the egg itself with 

 that number d . Others again have never more than six 

 legs : this is the case with Latreille's genera — Caris, 

 Leptus, Atoma, and Ocypetes of Dr. Leach e . In the 

 centipedes (Scolopendridce) and millepedes (Iulidce) dif- 

 ferences still more remarkable, as I have stated in a for- 

 mer letter, have been observed by De Geer ; these ani- 

 mals, in their progress to the perfect state, not only gain 

 several additional pairs of legs, but also several additional 

 segments of the body. This illustrious Entomologist found 

 that Polly xenus lagurus (Scolopendra~L.) was born a hexa- 



a De Geer vii. 197. b Ibid. 85. c Epist. lxvii. 1694. 390. 

 d Enum. Ins. Ausir. bio. e N. Diet. <T Hist. Nat. i. 74. 



