THE CHRYSALIS: EXTP:RXAL FEATURES. 27 



THE PUPA OR CHRYSALIS. 



Tlic foiiil oinlirai-c, tlio toiidoi- kiss 

 AVliicli li)\ (' to its cxprcssidn Ijrings, 



Are but the husk the ehrysalis 

 Wears on its wings. 



Alice C\ky.— Latent Life. 



External features. 



Chiysalids of butterflies present an outward appearanee essentially dis- 

 tinct from that of either tlie cater[)illai" or the imago. Quiescent in condi- 

 tion, organs of motion are useless, and are tlierefore enveloped in sheaths 

 and folded compactly upon and glued to the l)ody, which on its part is en- 

 tirely corneous for its better protection, and shows little of the primary 

 distinctions into head, thorax and abdomen. The head is seldom distin- 

 guishable from the thorax by anything more than a sutural impression, or 

 is slightly prominent, and although upon the upper surface there is a more 

 or less distinct regional contour clearly dividing the thorax from the abdo- 

 men, it is entirely concealed below by the appendages of both head and 

 thorax, which are those of the imago in a partially developed condition and 

 are extended in an almost common mass over the whole of the thorax and 

 half of the abdomen. In its forming condition all these organs can be 

 se^iarated from the body, but once hardened they are immovably attached 

 to it. 



It will, however, be both convenient and proper to treat of these diflTerent 

 regions separately, in order to obtain a better notion of the exact structure 

 of the insects in this stage. 



The head. The head is a more or less rounded compact mass of about 

 equal height and length but broader than either, usually occupying the 

 whole of the anterior extremity of the body, but in Lycaenidae crowded, 

 by the great expansion of the prothorax, entirely upon the under surface. 

 There are no distinguishable sutures dividing the head into regions or sec- 

 tions. The outer anterior portion, covering the eyes of the future imago, 

 is always more or less full, frequently protuberant and conical or pyrami- 

 dal, apparently for no other object than to protect the parts beneath, 

 although these would not seem to be so important in the economy of the 

 future insect as other cephalic organs which are not so carefully guarded ; 

 the position of the eyes, however, is such as to render them more liable to 

 injury, and it is noteworthy that these prominences are more marked in the 

 Nymphalidae which hang by the tail and swing in every breeze, and in the 

 Papilioninae (87 :6) which, although girt around the middle, have the ante- 

 rior part of the body projecting to an unusual degree, and being fastened 

 by a loose girth have some freedom of motion, than they are in the other 

 groups. In the Pierinae, however, the same object is effected by a single 

 anterior projection in the middle of the head, which in a gut chrysalis 



