802 INSECTA. 



V. Hymexoptera, (from vfiijv, a membrane, and msqov ) Wings mem- 

 branous ; anus aculeate. 

 VI. Diptera, (from 8voj, two, and TTTSQOf.) Wings two, with poisers in 



place of the posterior pair. 

 VII. Aptera, (from 8, without, and msgbv.) Destitute of wings or elytra. 



Fabricius, a pupil of Linnaeus, 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 Linnceus and Fabricius. The most pro- 

 minent of these is that by P. A. Latreille, who, in 1796, in his Precis des 

 caractercs gcneriques des Inr.ectes, 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. — APTERA. 



Order I. Thysanoura. Order III. Syphonaptera. 



" II. Parasita. 



II. — ALA T A. 



Order IV. Coleoptera. Order VIII. Hymenoptera. 



" V. Orthoptera. " IX. Lepidoptera. 



" VI. Hemiptera. " X. Rhipiptera. 



" VII. Neuroptera. " XL Diptera. 



The 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 antennae, the eyes, and 

 the mouth. The antenna? vary much in their composition and form. The 

 apterous insects, wnich form the first three orders, and the coleoptera, have 



