359 



gives us a picture of the wing-pattern of a certain ancestral 

 stage, but not of the most primitive one. 



This same stage is also repeated by the developing wings 

 under the pupal covering, but here it bears only a transitory 

 character, as it finally passes into the definite pattern of the 

 imago. As said above, the latter arises rather suddcnh-, and 

 from the beginning all its component markings show their 

 ultimate shape and boundaries. In this instance it resembles 

 the pattern of the pupal sheath, which also arises in a very 

 short lapse of time, and is at once finished in all its details. 



We may therefore conclude that this pupal pattern has 

 possessed its antecedent stages as well as the imaginai one, 

 and that these stages probably corresponded to the first vestiges 

 of colouring on the developing wings, which precede the full 

 display of what I call the primitive pattern. In the case of 

 the pupal wing-sheath these precursory stages must be com- 

 pressed into a few hours, partly before and partly after the 

 ecdysis leading to the appearance of the pupa. This fact 

 justifies the a priori assumption that thc\- will not manifest 

 themselves very clearly, and do not lend themselves well either 

 for fixation or for observation. What I saw of them during 

 the exuviation of the caterpillar's skin confirms this supposition : 

 the young wing-cases are transparent and show only very faint 

 traces of coloration. 



In both these features they dift"er from the colouring of 

 the body, especially the abdomen, which possesses a richly 

 developed pattern of different shades. This latter pattern 

 corresponds in its outlines, and also to a certain degree in 

 its colour-shades, to that of the full-grown caterpillar under 

 whose skin it has developed. Puulton seems to ascribe this 

 first coloration of the pupa to " the larval pigment still hngering 

 unchanged in the pupal hypodermis cells," and therefore "of 

 no morphological significance." I have not yet found leisure 

 to extend my investigations to the colouring of the body and 

 appendages other than the wings, but I believe that this study 

 wiU yield interesting results, and 1 presume that the abo\'e- 

 mentioned first and transient coloration of Üw pupal body 

 has a deeper significance than meaning only a mere lingering 

 behind of the caterpillar's pigmental distribution. I was \"ery 



