NOTES ON BUTTERFLY rui'^TJ, ETC. 103 



side pupal structure ; but I desire to direct attention chiefly to the 

 progress which is evident in the pup;\; of the Eiioi'ALOCEka, as in tliose 

 of Heterocera, from a condition of gi^eater to one of less freedom of 

 movement of the segments ; to the progress from a greater number of 

 exposed appendages (a decided " Micro " character) to a less number, 

 though this is not illustrated amongst butterflies except, perhaps, as 

 between Hesperids and Papilionids ; and to a general progress towards a 

 smootlily rounded, solid form, which, however, is greatly interfered with 

 amongst the butterflies by the exigencies of the develo])ment of })r(j- 

 tective resemblances. 



I am not aware of any instance in which a pupa appears to have 

 been derived from an ancestor which possessed a less number of 

 movable parts and, provisionally, I take it, as a rule, that movement is 



NEVER REGAINED BY A PUPA WHEN IT HAS ONCE BEEN LOST. That this 



should be so, is by no means self-evident but, as a matter of observation, 

 it appears to be the case. 



In the course of my study of pupa3 and of some other matters in 

 connection with Lepidoptera, the conclusion has forced itself upon me, 

 that a circumstance in the progress of evolution which I had believed 

 to be rather rare is really very common. This is, that similar structural 

 characters (sometimes one might almost say identity of structural 

 characters) have been reached along different lines by descendants 

 from a common ancestor, who did not present any indication of them. 



One of the most notable instances of this is to be found in the form 

 of pupa which I have described (Trans. Ent. Soc. Lon., 1893, p. 97) 

 as characteristic of the Maoko-Hetero('era ; that is, a pupa in which 

 the first four abdominal segments form part of the thoracic mass, the 

 5th and 6tli being free to move on their neighboui-s, wliilst the 7th, 

 8th, 9th and lUth form another solid piece. One might look upon tliis 

 arrangement as one, the attainment of which was regarded (if we may 

 use such language) as an object of ambition by the earliest Lepidoptera, 

 which as yet possessed freedom of movement of a majority of their 

 abdominal segments, and in which the 7th was still movable in the 

 male although not in the female pupa. Setting off along several 

 different roads, the structural arrangement mentioned above has been 

 arrived at more especially by the Macro-Hetehoceka. Whether it has 

 been reached by one or more routes I am not at all certain, but I am 

 disposed to think that amongst the Bombyces will be found groups that 

 have attained this condition of development indejiendently of one 

 another; I am not at all sure that the Pvkamdes do not represent a 

 separate line ; but, at any rate, it seems certain that the l)utterllies liavo 

 taken an entirely independent route. 



Like the pupa of the Macro-Heterocera, tliat of Fapilio (Figs. 

 1, 2) has got rid of nearly all "Micro" features; there is no dorsal 

 head-piece ; there are no maxillary palpi ; the antennas separate from 

 the head-piece on dehiscence {i.e., when the imago emerges) ; only the 

 5th and 6th segments are free, and these possess the power of move- 

 ment in all directions. There are, however, two earlier features 

 retained by the Papilionids which the Macro-Heterocera have lost ; one 

 of tliese is the possession of a waist, caused by the narrowing, chiefly by 

 dorsal depression, of the last thoracic and 1st and 2nd alHlominai 

 segments; the other is a certain amount of opening, on dehiscence, of 



