NOTODONTA TRITOPHUS. 73 



another on the twelfth, from which the outline sloped 

 down to the end of the anal flap. The third hump is 

 rather smaller than the others, but the humps change 

 their outline with the position of the body, as when 

 crawling it is sometimes in a straight line, and then the 

 humps are obtusely pyramidal and appear shorter 

 than when it is feeding or at rest in its more charac- 

 teristic attitude, with the back of the middle segments 

 more or less arched, and the three hinder segments 

 elevated free from the leaf or stem to which it is holding 

 with some or with all of the ventral prolegs. 



On the 18th of September its colour changed to a 

 dingy, blackish, velvety brown, or purplish-brown, the 

 head only remaining unchanged. In the evening it 

 spun up between two poplar leaves. (W. B., Note 

 Book IV, 150.) 



Ptilophora plumigera. 

 Plate XXXIV, fig. 2. 



I am glad to take this opportunity of acknowledging 

 my obligation to the Rev. Bernard Smith, for his 

 kindness in furnishing me from time to time with a 

 great variety of subjects for my pencil, as well as for 

 the repeated supply of eggs of plumigera in 1869 and 

 1870, by means of which I have been enabled to work 

 out the transformations of this rare and local species. 



The eggs are laid in November, either singly or in 

 little groups of two or three together on the young 

 brown shoots of maple (Acer campestre), to which they 

 assimilate well. The shape of the egg is like a conical 

 button, being of a blunt-topped obtuse cone, rounded 

 off a little towards the broad base and a little depressed 

 beneath ; sometimes it is not quite regular in shape, 

 and the top instead of being just in the middle of the 

 upper surface is nearer one side than the other. As 

 to its colour there is generally on the rounded apex a 

 circular whitish spot surrounded by a broad ring of 



