Holvtesdale Natural History Club. 



however, is not the divergence of forms of the chrysalides, but the transition 

 to the perfect insect, so that I will assume that development of the imago 

 has duly taken place within the pupa (the physical consideration of which 

 forms no part of our subject this evening). The actions then set up previous 

 to extrusion are as follows : — 1st, change of position ; 2nd, change of 

 colour ; 3rd, appearance below the surface of imagal markings, or additional 

 ornamentation of the pupa ; 4th, transparency of eye-coverings and other 

 parts of pupa-shell ; 5th, lengthening of the abdominal segments, which 

 last is generally immediately before emergence. Now the first remark on 

 these changes is that there is a period of repose of uncertain duration 

 between each. This must of necessity be for the purpose of re-adaptation 

 and alteration of the internal fluids and viscera for the purpose they are 

 finally destined to fulfil, an alteration better carried out in repose, as well as 

 more consistent and certain in its effects ; for we must reject Reaumur's 

 theory that " all insects know the day of their final change, and that 

 instinct teaches them to economise, or rather fill up the time leisurely." 

 If this were so the duration of the pupal condition would always be the 

 same, modified, but only slightly, by bad weather or drought, a state of things 

 ■which we know to be at variance with our experience, and one which would 

 lead to frequent extirisations of species, if not classes and orders. Further, 

 these changes almost invariably occur in the order of rotation named, but 

 from the different modes of pupation adopted they are necessarily but 

 indistinctly seen, it being as little desirable to disturb pupa as garden 

 seeds when once below the surface of the ground. It would be taking up 

 your time unnecessarily to enter more at length into these general 

 movements, peculiarities in which I shall draw your attention to further on, 

 but having mentioned different forms of pupation it will be desirable to see 

 how far these affect the emergence of the insect. Of the Diurni the genera 

 chiefly reared in confinement are Papilio, Pieris, Melitfea, and Vanessa. 

 The changes they undergo are too well known to require attention, but the 

 transitional stages of the equally common Pyrarga, Bgeria, Polyommatus, 

 &c., have been little cared for, and even the descriptions of the larvas are 

 copied from the works of continental writers. I myself have, through the 

 kindness of a friend, made the acquaintance of some of these for the first 

 time this year, and I take tKis opportunity to exhibit pupa-cases, which 

 may interest those present. Where the pupa is suspended, as in the case of 

 many of the Diurni, the colouring, by being intensifled, often obscures the 

 markings, which are thus lost sight of shortly before emergence, particu- 

 larly of the dark-garbed species. The chrysalides of these common insects 

 are but little known to English collectors, excepting by plates in text- 

 books, though curious and interesting. That of Tithonus is a beautiful 

 object, and one of the few instances we have of simple ornamentation in 

 this phase of life. The late Mr. Newman, in his " History of British 

 Butterflies," describes the colour of the chrysalis of Tithonus as almost 

 white, tiuged sometimes with green, and ornamentei with numerous black 

 jnarkings, but that of Janira as pale apple-green, freckled with whitish or 



