14 
except one pair of Z's and perhaps one pair of M’s. He refrained at 
present from any inferences as to the cause of the sterility of the 
third generation of forced moths in the A and Z lines, but 
thought it would be prudent in these experiments to include 
some selections from points in the scale of size considerably short 
of the extremes. All the successive generations were of the 
summer type (Juliaria). In all the female was on the average 
sensibly larger than the male, but in the natural spring emergence 
the reverse was the case, S. illunaria was the only English 
double-brooded Geometer, exeept perhaps, 7. laricaria, which had 
one of its emergences in a winter month, and he threw out the 
suggestion whether the relatively smaller size of the female in 
the first emergence might be a step towards or a remnant of 
apterousness, usual in the female of our winter moths. It would 
be interesting to breed and compare 7”. laricaria. He could not 
undertake any other species than ilunaria and illustraria, and 
circumstances might interfere even with them ; and as the experi” 
ments with them must continue for many generations in order to 
reach the results wanted for Mr. Galton’s purposes, and required 
uninterrupted watchfulness, it was essential, to prevent an 
accidental failure, that there should be a second line of experi- 
ments conducted independently. Both species were very easy to 
rear, and offered much scope for experiment in various directions ; 
he would gladly supply eggs in the spring for the purpose. Mr. 
Merrifield further said he should be glad to be afforded the 
opportunity of seeing and, if judged expedient, breeding from 
unusual varieties or types of either species, or examples from 
Ireland, Wales, Northern regions, such as Scotland and 
Scandinavia, where both species appear to be single-brooded, or 
from Central or Southern Europe. The resting position of the 
Selenias was remarkable ; illunaria, folds its wings closely 
together like a butterfly, and illustraria holds them at an angle 
of 50° or 60°. He exhibited two diagrams, one shewing the 
measurements of the successive broods, and the other the 
duration of the larval and other stages in each ; also a number 
of specimens of each brood of illunaria, and several of ilustraria. 
