76 Descriptions of Preparations. 



iind Bau der Gliederthiere^ pp. 78,, 87^ 88 j Rathke^ Mor- 



jjliolog-ie, pp. 136-127. 

 For the antennae of the larvae in relation to those of the imago, 



and the antennae and antennules of Crustacea, see Zaddach, 



1. c. pp. 13, 86, 89. 

 For a history of the metamorphoses of Lepidoptera, see Westvvood, 



Introduction to the Modern Classification of Insects, vol. ii., 



pp. 310-321. 

 For figures of the oral organs of the Larvae of Lepidoptera, see 



Lyonet, Traite Anatomique de la Chenille qui ronge le bois 



de Saule, pi. i. ii., and p. 59 for functions. 

 For those of the imago, Savigny, Memoires sur les Animaux sans 



Vertebres^ vol. i., pi. i, ii. iii. 



26. Pupa of Death's-head Moth 



{Achero7itia Atropos), 



Showing the form of chrysalis known as 'obtected,' or better, as ' larvate' 

 or ' signate.' 



In this form the external organs of the future perfect insect are 

 more or less obscurely distinguishable beneath the hard elastic 

 membrane in which they are inclosed instead of being free as in the 

 so-called ^ exarate^ or 'liberae* pupae of Coleoptera and Hymen- 

 optera, and which is a product of the hardening of a secretion 

 instead of being merely the dried integument of the maggot, as 

 in the ' coarctate^ pupa of many Diptera. The conical form of the 

 pupa case is characteristic of the Heterocerous Lepidoptera, in 

 contradistinction to the angular form of the Rhopalocerous. The 

 apical portion of the cone, the 'cremaster^ of Kirby and Spence, 

 is made use of by the pupa when it works its way up from the 

 chamber, six inches or so deep in the ground, before entering 

 upon the imago-stage of its existence. In possessing thus a 

 power of motion in the last stages of their pupa-life, the Lepi- 

 doptera resemble the Phryganeodeae or ^ caddis flies,^ as they do 

 also in many other particulars, though the chrysalis of the family 

 just mentioned differs from that of the Lepidoptera in being 

 ' free ' or ' exarate ' like that of the beetles and bees. Seven 

 spiracles are seen on cither side upon the abdominal segments; 



