23i STATES OF INSECTS. 



this web without going wholly out of it. The third is 

 the most curious and remarkable of all. It is nearly six 

 inches long, and about four-fifths of an inch in diameter. 

 It consists of a bag of thick cinereous silk web, to which 

 are fastened, in a sextuple series, pieces of stick about an 

 inch long, the end of one mostly resting upon the base of 

 another: between each series a space of about three-tenths 

 of an inch intervenes, but at the apex they all converge. 

 This probably imitates the branch or stem of some tree 

 or plant, in which the leaves are linear, and diverge but 

 little from the stem. A label upon it states its country to 

 be New Holland. I suspect the inhabitants of the two 

 last cocoons to be terrestrial animals : the first is proba- 

 bly a true aquatic case-worm. 



The same purpose for which the cocoons above de- 

 scribed serve, is answered in the case of numerous Di- 

 pterous insects, by a humble and less artificial contriv- 

 ance — the skin, namely, of the larva ; which, as was be- 

 fore observed a , is never cast, but, when the insect is about 

 to enter into the pupa state, assumes a different form and 

 colour; becomes of a thicker and more rigid texture; 

 and defends the included pupa, which is separate from it, 

 till its exclusion. In this case the mouth of the larva is 

 constantly different from that of the perfect insect, or at 

 least has not with it those relations as to number and 

 kind of organs, which have been observed in the mouth 

 of other larvae compared with the insects that they pro- 

 duce. The animal, immediately after it is clothed with 

 this skin, if it is opened, exhibits only a soft gelatinous 



a See above. Vol. I. p. 67. 



