THE EXTEENAL MOKPHOLOGY OP THE LEPID0PTEE0US PUPA. 61 



remarkable bloom found on the surface of the pupae of Catocala, 

 Cosmia, Halias, Pamassius apollo, &c. The substance which produces this 

 appearance is a kind of wax and, on the pupa of the latter species, which 

 is completely coated with it, the material is so thick that it can be scraped 

 off. Chapman finds that it melts, is perfectly insoluble in water, and 

 that water runs readily off it, and there appears to be no doubt that it 

 is a water-proof coating for the protection of the pupa, in its sometimes 

 damp haunts. The pupa of Pyrgiis galba, from Mhow in north-west 

 India has a similar surface bloom, almost as thick as that of Par- 

 nassius, whilst Walker notes that in Chile the pupa of Ala mis poliodes 

 is covered with a white mealy powder. As the pupa is always placed 

 in a slight cocoon under stones, it is possibly of the same nature as the 

 resinous bloom of the Catocalid and Parnassiid pupae. 



We have already divided lepidopterous pupae into three groups — pupae - 

 liberae, pupae -incompletae, pupae-obtectae — and have stated that one of 

 the essential differences of the two last consists in the number of movable 

 abdominal incisions possessed by the pupae, in other words the number 

 of " free segments " they exhibit. The pupa-incompleta varies some- 

 what in the actual number of movable incisions, and these, as a rule, 

 show a sexual variation, the 7th abdominal segment being free in 

 the male, fixed in the female ; it thus presents characters that bring it 

 into line with those of bees and beetles. On the other hand, the obtect 

 pupa is remarkably constant in this matter, having the 5th and 6th 

 abdominal segments, and these only, free in both sexes. This pupa 

 usually presents a hard chitinous exterior, the appendages, legs, wings, 

 &c, lying together, forming a smooth, hard and solid exterior, whilst 

 the surfaces that are hidden by being applied against each other are 

 formed of a delicate skin, represented, when the moth emerges, by a few 

 flimsy shreds, the previous position of which it is almost impossible to 

 determine, so that the empty pupa-case consists almost entirely of that 

 portion which formed the outer covering. In the pupa-incompleta the 

 exposed surface is usually less solid, but the skin of the covered sur- 

 faces is much tougher (than are those of the pupa-obtecta) and, on the 

 emergence of the imago, the pupa hangs together so that the nature 

 of each portion is rarely difficult to determine, and some parts, e.g., 

 the inner wing-coverings, the portions of the abdominal segments 2 

 and 3 covered by the wings, and the intersegmental membranes 

 are only a little less firm than the coverings that are fully exposed. 

 On dehiscence, these covered portions become exposed, the appendages 

 show a certain independence of each other never observed in an obtect 

 pupa, and, even, before emergence, the appendages separate and the 

 segments open out without any fracture or tearing occurring. 



On the dehiscence of an incomplete pupa the head-coverings separate 

 from the rest of the pupa, yet remain attached to one another in one 

 piece. These head-parts consist of the plate covering the head and eyes, 

 the antennae, and the mouth-parts. In the obtect pupa these parts 

 frequently separate from each other — the head-cover forming one piece, 

 the antennae separate, the mouth-parts also may be separate, but more 

 usually they remain attached to the legs in one piece, the antennae going 

 either with these or with the wings, whilst in the few cases (Sphingids, 

 Bombycids, Notodonts, &c.) in which the head-coverings remain in one 

 piece, they do so because they remain attached to the leg- or wing- 

 coverings ; they never remain in one piece when detached from the rest 



