STATES OF INSECTS. 251 



legs, except in the case of some sphinxes, which I shall 

 notice afterwards : so that the eiosso-theca covers both 

 them and it. 



3. The abdomen-case consists of ten segments when 

 viewed on the back, and of only six when viewed below ; 

 so that it might be said to have ten dorsal and six ven- 

 tral segments : but the fact is, that the place of the three 

 anterior ventral segments, or rather ventral portions of 

 the segments, (for they form complete rings without any 

 lateral suture, ) are replaced by the wings and other or- 

 gans : in consequence of this, the fourth segment, which 

 is less covered than the three first, at its posterior margin 

 forms an annulus or ring. In counting the abdominal 

 segments of a pupa, you must be careful not to include 

 the piece that represents the metathorajc, which looks as 

 if it belonged to the abdomen a . In the pupae of butter- 

 flies you will discover evident traces of ten dorsal seg- 

 ments ; but in many moths, and some hawk-moths, you 

 will perceive at first only eight, or even seven, but a closer 

 examination will enable you to discover the line that 

 marks out the others ; and if you divide the puparium 

 longitudinally, and inspect its internal surface, you will 

 see very visible sutures between them. The intermediate 

 segments are sometimes separated from each other and 

 the preceding and subsequent ones by deep channels. 

 In the pupa of Papilio Machaon there is one such chan- 

 nel between the third and fourth segments. In Bombyx 



a The caterpillar consists of twelve segments (Lyonnet t. i.f. 4,5), 

 excluding the head ; on each of which, except the 2d, 3d, and 12th, 

 there is a pair of spiracles. The chrysalis usually exhibits an analogy 

 to this structure, though the first, second, and last pair of spiracles 

 are more or les3 obsolete in most. 



