142 
scales, called plumules, have long been known ; but examina- 
tion with the binocular microscope shows that they are not 
flat like the ordinary scales, but cylindrical and hollow. 
They have been found only in certain genera (named in the 
paper) at present, and on the males alone ; they possess 
generic resemblances and specific differences, each species 
displaying its own distinguishing variety. One of great 
beauty and novelty, found only on two African butterflies, 
Pieris Agathina and Pieris Chloris, Avas described, and some 
very fine drawings of it, by Mr. Joseph Sidebotbam, were 
exhibited, and also other figures by him of about one hundred 
species never figured before. The names and habitats of the 
m 
insects Avere given, and the Author pointed out the value of 
these scales for the assistance of the scientific entomologist 
in arranging genera and species; be then entered into the 
question of their probable use as air vessels in the economy 
of the insects possessing them. 
The Chairman remarked that the scales of the Lepidoptera 
may prove to be as valuable in determining species as the 
scales of fishes. 
Mr. Sidebotbam alluded to the value of the binocular 
microscope in defining the cylindrical form of the plumules, 
and described the mode of finding them in situ, by breaking 
the Aving. 
Mr. Watson stated that some of Mr. Sidebotham’s excel- 
lent drawings were taken under the eighth objective, magni- 
fying 750 diameters. Mr. Watson further said that he had 
examined the wings of 400 specimens of the Papilionidae, 
but had not discovered any plumules in that genera ; he also 
alluded to several so called species from South America, of 
Avhicli no males have yet been found, others of Avhich no 
females have yet been discovered, and suggested the possi- 
bility of some of these being male and female of the same 
species ; to ascertain Avhich, careful examination of the scales 
might be useful. 
