74 
On the Battledore 
[iMonthly Microscopical 
Journal. Aug. 1, 1869. 
the bulb is very liable to be broken off ; they are mucb more nume- 
rous on some species than on others, and tbeir number varies con- 
siderably even on individuals of the same species, especially at dif- 
ferent periods of existence. The males alone possess them ; none 
are ever found upon the females. They have been called " plumules " 
by some authors ; and those of Pieris Brassicse, P. Bajpw, and 
P. Na^i (our common white garden Butterflies), are well known to 
microscopists, and were formerly called test-objects. 
In the *Annales des Sciences' for February, 1835, there is an 
interesting article on the organization of the scales of Lepidoptera, 
by M. Bernard Deschamps. It is principally devoted to the con- 
sideration of the structure of the scales, as composed of several 
lamellae or membranes ; of the mode in which they are affixed to the 
wings ; and of the place in which the colouring matter is deposited. 
He also refers to these plumules, and gives figures of a few of them : 
he does not suggest any peculiar use for them, but draws attention 
to the fact that the males alone possess them, and that they have 
some general resemblance, with certain specific dijBferences. He 
examined and figured seven species of the Pieridse, to which family 
I am about to allude. My friend Mr. Sidebotham has most kindly 
and laboriously drawn the plumules of about one hundred species of 
Pieridae observed by me, very few if any of which have been figured 
before. 
According to the modern arrangement of Doubleday, Westwood, 
and Hewitson, the family " Pieridae " consists of sixteen genera, and 
in seven of them, viz. Euterpe, Pieris, Anthocharis, Idmais, Thestias, 
Hehomoia, and Eronia, I have discovered plumules.* There are 
several distinct types of plumules, generally more or less running 
into one another; but each species possesses its own peculiarity, 
with diversity sufficient for identification, while in each individual of 
the same species there is always the same form of plumule. These, 
therefore, must afi'ord to the scientific entomologist a valuable test 
in the determination of closely allied species, and it is probable that 
they may serve to form congenial natural groups and subdivisions 
in some of the genera. 
It is remarkable that the peculiar and well-known plumule of 
Pieris Rapm should prevail, in a generic and very similar form, 
also in P. Napi, P. Gruciferarum, and P. Gliciria (the first two 
European, the third North American, and the fourth Chinese). 
These insects are of close affinity in other respects ; and in other 
instances congeniality of plumule is found in nearly allied insects. 
The most remarkable and beautiful form of plumule, now for 
the first time observed, as far as is known to the writer or others 
to whom it has been shown, is that found on Pieris Agathina 
* The examination extended over about 300 species ; and I found plumules in 
cill the male specimens, "with three exceptions. 
