lepidopterous larva; and pup (E. 151 



Although there seems to be some difference between 

 the two sections of the obKque borders (being dark brown 

 above and a Hghter reddish brown below), there is not 

 so sharp a demarcation as in the other variety. There 

 is apparently no trace of the oblique stripes, although 

 there is the linear light coloured posterior edge to the 

 inferior anterior section of each border (as in the yellow 

 variety). 



In one of the specimens I was very interested to find 

 a distinct trace of the subdorsal line, which is present 

 (as in the adult whitish varieties of Smerinthus occllatus 

 larvae) as the demarcation between a lighter dorsal and 

 a darker lateral tint, the junction being itself slightly 

 lighter than either. Traces of the line were also visible 

 on the thoracic segmente, and the whole marking was 

 especially well seen on looking at the larva from a little 

 distance so as to obtain a general impression. 



Again, the traces of the shagreen dots on the dorsal 

 surface are far less modified than in the other variety, 

 and are accompanied by less altered dots, which are 

 similar to those uj^on the lateral and ventral surfaces. 



Those which are modified are larger than the others 

 and have small circular reddish patches round their 

 centres, which are marked by the scar of the bristle 

 which formerly existed in this position. Below the 

 oblique borders traces of shagreen dots are very abundant 

 and distinct, being especially crowded upon the dark 

 ventral surface. Each is a light-coloured circular patch, 

 which is not raised above the larval surface. Within 

 each patch is the dark scar, with a minute central white 

 point, which appears to be sometimes developed into the 

 rudiment of a bristle. The prominence of these lower 

 patches affords a strong contrast to their condition in 

 the yellow larvae. 



Hence this strong contrast between the markings of 

 the two varieties in a dimorphic species (quite apart 

 from their difference in colour) seems to suggest that 

 they may have originally belonged to different stages in 

 the ontogeny. Whatever be the interpretation, it is 

 quite clear that the differences are of a much more 

 strongly marked kind than those usually expressed by 

 the term " dimorphism " as applied to larvae. 



I should be extremely glad to be able to work out the 

 ontogeny of the larva of A. atrupos, but unfortunately 



