802 INSECTA. 
V. Hymenoptera, (from tuyv, a membrane, and ategov ) Wings mem. 
branous; anus aculeate. 
VI. Dirrera, (from dum, two, and wtegdy.) Wings two, with pcisers in 
place of the posterior pair. 
VII. Aprera, (from c, without, and mtegdv.) Destitute of wings or elytra. 
Fabricius, a pupil of Linnzus, proposed an arrangement of insects, found- 
ed on their instruments of manducation. De Geer had, indeed, in the 
majority of his classes, added the characters derived from the mouth, to 
those afforded by the wings; but Fabricius carried the principle much far- 
ther, and made the Trophi, or Instrumenta Cibraria, as he termed them, the 
basis of all his divisions. ‘To the labors of Fabricius, entomology is deeply 
indebted; for independently altogether of the merit of his arrangement, as 
an artificial system, it had the effect of directing the attention of his suc- 
cessors to parts indicating a corresponding difference in the character and 
‘structure of the animals. Subsequent writers have proposed various sys- 
tems, combining the characters of Linneus and Fabricius. The most pro- 
minent of these is that by P. A. Latreille, who, in 1796, in his Précis des 
caractéres génériques des Insectes, limited the definition of the class, and 
whose object in his subsequent writings has been to divide his orders into 
natural groups. Cuvier, Lamarck, and others have also done much to in- 
crease the anatomical and general knowledge of insects, and to facilitate 
their study by appropriate arrangements; and Mr Macleay has suggested a 
very ingenious classification, founded on the quinary system, by which it 
appears that the groups, when arranged in circles of five, seem mutually 
connected together. Latreille divides the class of insects, as now restricted, 
into eleven orders. 
I.—APTERAz ' 
Order I. THYSANOURA. Order III. SypHoNArPreRa. 
“ TI. Parasira. 
II.—ALATA. 
Order IV. CoLEopTERA. Order VIII. HymenoptTera. 
ss V. ORTHOPTERA. es IX. LEprmDorrera. 
« 6VI. Hemrrera. ee X. RHIPiIPrera. 
“ VII. Nevrorrera. < XI. Diprera. 
fhe body of insects is divided into three principal parts, the head, the 
thorax, and the abdomen. The head, of which the surface bears many 
names, according to the position of its parts, such as the vertex, the fore- 
head, the nose, the hood, and the cheeks, supports the antenne, the eyes, and 
the mouth. The antenne vary much in their composition and form. The 
apterous insects, wnicn form the first three orders, and the coleoptera, have 
