174 PROCEEDINGS OF SOCIETIES. Rosen cng 
as some expressed it, the formation of tails. This was considered by 
no means the least interesting part of the evening’s display. Mr. Peake 
exhibited the pygidium of the lace-wing fly, Chrysopa perla, discovered 
by himself. The existence of this peculiar structure has long been 
known in the flea, but has not been pointed out in any other insect. 
Dr. Kebbell exhibited with a Nachet’s prism the rasping teeth situated 
on the disc of the proboscis of the blow-fly. Mr. Smith showed fruit 
of Hepatice and Epicarpal Stomata of moss, funaria. These are only 
found on the fruit of mosses, and never on the leaves. Mr. Hennah 
showed plant circulation in the hairs of the Tradescantia, spider-wort, 
and remarked that every microscopist should possess a root of this 
plant in his garden ; pollen showing the production of the pollen-tubes; 
Desmidex, mounted five years since in the water in which gathered, 
with the endochrome perfectly preserved ; and Caprellz, from Black 
Rock, Kemp Town, &c. Mr. Wonfor exhibited a slide of Diatom, 
mounted by Miiller, of Holstein, on which, in the space of a quarter 
of an inch, 408 separate silicious skeletons of plants were arranged 
in symmetrical rows. This slide, which was a marvel of skill in micro- 
scopic mounting, arrangement, and perfection of specimens, was kindly 
lent for the occasion by Mr. T. Curteis, of Holborn. It was to the 
student of this department not simply a wonderful slide, but a cabinet 
of objects; in fact, a printed catalogue lay by the side of the micro- 
scope for reference to any particular valve; live caterpillars of the 
emperor moth; very gorgeous crystals of hematoaylyn, the colouring 
matter obtained from logwood; artificial alizarine, prepared from an 
oil of coal gas. The discovery of this substance is regarded as a great 
triumph in chemistry, as it resembles the red dye obtained from madder ; 
polyzoa, and other interesting objects. 
In addition to these microscopic objects, Dr. Hallifax exhibited a 
number of beautiful micro-photographs of his own taking ; and Mr. J. 
Howell, pebbles picked up on the beach, showing encrinites, penta- 
crinites, bryozoa, cidaris spines, &c. 
June 9th. Ordinary meeting.—Mr. Sewell, Vice-President, in the 
chair. 
A paper “On Diptera and their Wings,” by Mr. Peake, was read 
in the absence of that gentleman by Mr. Wonfor, Hon. Secretary. 
While wings are common to the whole order of insects, the Diptera 
consist entirely of two-winged flies, which, instead of a second or hinder 
pair, have little thread-like bodies terminated by knobs and called 
halteres, originally considered balancers, supposed now by some to be 
organs of hearing, and by others olfactory organs. From many points 
of resemblance, he thought they were analogous to the hind wings of 
other insects, and that, at present, their special use had not been ascer- 
tained. Besides these halteres, they had also winglets (alule), which 
were thought to be only appendages to the fore-wings. Among the 
Diptera three classes of fliers were found, differing in the form of their 
bodies and shape of their wings; first, the slender flies, such as the 
gnats, having long bodies, narrow wings, and long legs, but without 
winglets ; secondly, those whose bodies, though slender, were more 
weighty, as the Asilidee, having larger bodies, shorter legs, and very 
