FROM EMBRYOLOGICAL DATA. 11 



brown, or blackish. Of the following abdominal rings, the first and second, or the 

 fourth and fifth behind the head, are deprived of locomotive appendages, but the 

 third, fourth, fifth, and sixth, or sixth, seventh, eighth, and ninth, are provided 

 each with a pair of ambulatory feet, the extremity of which is surrounded by a 

 crown of minute hooks. The next two joints are deprived of legs, but the last 

 joint is again provided with a pair of prolegs, differing somewhat from the middle 

 ones in being more compressed laterally. 



With these characters the caterpillar arrives at its maturity, and when it has 

 done eating, after walking about for some time in search of a convenient place for 

 its transformation into a pupa, fixes itself with some silk threads by the tail, throws 

 a few others across its body, and spins a very thin, transparent, loose cocoon, or 

 rather a kind of incoherent net, between the leaves which it folds around itself, 

 and remains quiet to undergo its first great change, and to pass into the state of 

 chrysalis. (Fig. 7.) 



The first marked modification from its former condition consists in a general 

 shortening of the body. (Figs. 8, 9, 10.) The whole larva contracts for about one 

 third of its length, and thus assumes permanently a position which it shows some- 

 times when at rest. But even after it has thus become quiet, it will, when dis- 

 turbed, again move about in search of a more protected shelter. 



If left undisturbed, the body is seen to swell, especially in its anterior part, 

 which seems to be in a state of chronic inflammation, as it were, having the 

 appearance of an cedematous swelling, distended by a considerable accumulation of 

 lymph. 



The thoracic region and the head are at this time the chief seats of the forma- 

 tive process, and of a more active process of nourishment ; the other parts seeming 

 rather to wither, the skin to shrivel, and the prolegs to dry up. Indeed, before 

 long, the skin of the larva is sufficiently loose to be separated without much diffi- 

 culty from the pupa forming underneath ; and by watching carefully the moment 

 when the skin splits upon the back in the process of being naturally removed, the 

 whole process may, with some assistance, be accelerated, and the skin turned away 

 before the chrysalis is entirely formed. (Figs. 11, 12, 13.) At this moment the 

 young animal presents characters so different from the perfect pupa, that, unless the 

 whole process has been carefully watched, no one would suppose that the forms it 

 then exhibits are really the next transformation of the larva towards its change 

 into a chrysalis. 



Indeed the chrysalis, when perfect (Fig. 7, 7 a, 7 6), presents a hard case, upon 

 which, with some attention, we may distinguish the outlines of the abdominal joints 

 and the thorax ; upon the sides of this, and below it, an outline of the future wings 

 may be recognized, as well as superficial indications of the legs underneath, bent 

 backwards between the wing-covers ; there is likewise a tubular flattened case, 

 representing the antenna? ; and upon the middle line, a similar one answering 

 to the proboscis. (Fig. 7.) All these parts are soldered together, and upon the 

 skin itself, so closely as to be entirely immovable, and to appear rather as a pro- 

 tecting envelope of the organs, the form of which they foreshadow, than as these 



