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PROCEEDINGS OF LEARNED SOCIETIES. 
ROYAL INSTITUTION OF GREAT BRITAIN. 
March 9, 1866.—Sir Henry Holland, Bart., M.D., D.C.L., F.R.S., 
President, in the Chair. 
On the Metamorphoses of Insects. By Sir Joan Lusrock, Bart., 
F.R.S., M.R.I., Pres. Ent. Soc., V.P. Lin. Soc., V.P. Ethn. Soc., 
F.S.A. 
Tue subkingdom Annulosa, to which insects belong, is divided into 
five classes, namely, Annelida, Crustacea, Arachnida, Myriopoda, 
Insecta. 
The Annelida, or worms, have a body consisting of more or less 
numerous segments, but without any jointed appendages. 
The Crustacea, or crabs and lobsters, have a jointed body, and each 
segment usually bears a pair of appendages. They are aquatic in 
their habits. 
The Arachnida, or spiders, possess four pairs of legs; the body is 
divided into two parts, the cephalothorax and abdomen. The seg- 
ments composing the abdomen bear no appendages. Spiders are aérial 
in their habits. 
The Myriopoda, or centipedes, have a long body consisting of 
numerous segments, each of which bears a pair of legs. 
The Insecta, or insects, have three pairs of legs. They are aérial 
in habits, and breathe by means of tracheze or air-tubes, which ramify 
throughout the internal organs. The body is divided into three parts, 
the head, thorax, and abdomen. 
In addition to the three pairs of legs, the thorax bears generally 
either two or four wings. The older naturalists collected the wingless 
forms into a special order—the Aptera; but more extended observa- 
tions have shown that each of the large orders or groups into which 
insects are divided contains some apterous forms. The female glow- 
worm and the working ants are familiar examples of this. 
But though the presence of wings is the rule, and the division of 
insects into orders is founded in great measure on the characters 
afforded by these important organs, still they are present only in the 
mature state of the animal, and no known insect is born with wings. 
Not only in the absence of wings, but also generally in many other 
important points, the young insect differs from the mature form, and 
the changes which it goes through are known as metamorphoses. 
Entomologists have generally considered the life of all insects to be 
divisible into four well-marked periods—that of the egg, the larva 
or caterpillar, the pupa or chrysalis, and, finally, the imago or per- 
fect insect. It is true that in some orders, as, for instance, the Coleo- 
ptera (beetles), Hymenoptera (bees), Lepidoptera (butterflies), and 
Diptera (flies), the larvee differ much more from the perfect insects 
than is the case in others, as, for instance, the Orthoptera (grasshop- 
pers) or Heteroptera (bugs) ; but even in these latter the stages were 
still supposed to be well marked,—that of the larva, by the entire 
absence of wings ; that of the pupa, by the possession of rudimentary 
wings ; finally, the perfect insect, by having perfect wings. 
