pupa with functionally active mandibles. 265 
Macro pupa possesses this habit, though certain details, 
both of structure and habit, differentiate these cases of 
Macros from the ordinary habit of Incomplete. Mr. J.E. 
Robson also calls my attention to the habit of the pupa 
of Lasiocampa rubi of travelling up and down in its 
cocoon in order to make the most of available sunshine. 
All these cases seem to me to be re-acquirements, 
by Macros that had long lost them, of the primeval 
habit of Incomplete. 
I have observed in some Macros a structural point, 
giving strong confirmation to the idea that the Macros 
are a much younger form than the Micros. In some 
species the male pupa has a more marked incision be- 
tween the 7th and 8th abdominal segments than the 
female has, even at times looking as if this articulation 
admitted of movement. This is never the case, but it 
appears to prove unquestionably an ancestry with the 
7th segment ‘‘free” in the male to a later period than in 
the female. 
tT 2 
