12H THE ENTCMULOUIST's RECOKl). 



slij^ping forward does not occur, in many cases at all events, until the 

 girth has had time to impress its marking across the wing-covers. It 

 must occur whilst the pupa is still soft and capaljle of some activity, 

 but I have not seen how it is accomplished. The peculiar curved 

 attitude of the larvae of Enchlo'e and Coiias, after si;spension but before 

 pupation, may afford a hint as to how the shift originated. When the 

 girtli did so sliiJ forwards, one of two things would happen : either the 

 pupa would swing free, thus leading to the Nymphalid type ; or the 

 girth might catch on the projecting nose-horn, and in time lead to the 

 structure and habit thot characterise Thais. I may note that the pupa 

 of IViais has both the 5th and 6th abdominal segments free and with 

 power of movement in all directions ; so far, therefore, it is clearly a 

 Papilionid rather than a Parnassid or a Pierid. The nose-thread is a 

 loop, exactly such as the girth slipjjed forwards would be ; it passes 

 forwards from its points of origin to the nose, whilst there is a groove 

 marked on the wing-covers, that is exactly in a line from the same 

 points of origin, backwards (tig. 3). A close examination of a number 

 of specimens shows no trace of any other girth than this nose-looj), 

 either on the })U})a itself or in the form of any attacliment to the silk pad, 

 which is smooth and finished throughout, and clearly has not had any 

 other loop torn from it or removed. That the pupa is tolerably active 

 when the slipping forward takes place is evidenced by the nose having 

 twisted itself into a second loop of the girth round the hooks in many 

 instances. 



Thais, however, did not lose the girth entirely and so become a sus- 

 pended pupa like the Xymplialids. It is, as we have seen, one of several 

 forms, that do not lead directly' to Parnasmis in lineal (_)rder, but appear 

 to have branched off from the Papilionids at the same time. In the 

 Pierid we have a Papilionid that has lost the power of lateral move- 

 ment, probably in connection with the method of suspension by a girth. 

 The Nym})halid is a Pierid that lias lost the girth. This close connec- 

 tion of the Pierids and Nyraphalids is one that has not apparently been 

 hitherto insisted on. The form of the egg is the same in )>oth, and 

 differs from that of the Papilionids, which retains the smooth dome- 

 shaped form characteristic of the egg of the Hesperids. Again, the 

 restriction of movement to the lateral direction is very remarkable, for 

 it occui's 7iowhere else ; and, since it exists throughout both these 

 nearly related families, it seems reasona))le to assume that it is a common 

 inheritance and not a separate acquisition, especially as it is obviously 

 useful to the Pierid but of no obvious value to the Nymphalid, in 

 which it ])ersists only because movement once lost is never regained 

 (at least this rule holds so generally true, that we may reasonably apply 

 it here in explanation.) But, accepting this explanation, it follows, that 

 the divergence must have taken place whilst the Pierids still retained 

 both the ;")th and Gth abdominal as movable segments, as is still the 

 case in Apvria, Delia.^ (fig''- 6-7-8) etc. ; and further, seeing that the 

 Nymphalid ])reserves the double nose-hoin of the I^ajiilionid it must 

 have taken ])lace Ijefore the Pierid was reduced to a single median one, 

 and it is interesting to note that Delias, one of the earliest I'ierids, still 

 affords some evidence of the former presence of a double nose-horn 

 in the Pierids. Our own A. cratct^iji does so iu a less degree. 



A consideration of these pupal characteristics, as well as of those of 

 the eggs, leads me to believe that Pierid and Nymphalid started 



