10 MODERN CLASSIFICATION OF INSECTS. 



niptera, the organs are all exposed, the upper lip, mandibles, and 

 tongue elongated, the maxilte and labium short and furnished with 

 articulated palpi. It is called rostrulum by Kirby and Spence, and 

 rostellum by Latreille, which latter name had been previously em- 

 ployed by Kirby and Spence for the mouth of the Pediculus, but 

 which Latreille has termed Siphunculus. 



The Thorax, on account of its being the chief seat of the various 

 organs of motion, is extremely complicated and variable in its struc- 

 ture ; and it is only within a few years that its investigation has been 

 philosophically entered upon, or a concise nomenclature of its parts, 

 founded upon such investigations, proposed. It is the truncus of 

 Linnaeus, and comprises the three segments following the head, which 

 have been respectively termed prothorax, mesothorax, and meta- 

 thorax, which were originally proposed by Nitzsch. The first of 

 these segments bears the anterior pair of legs, the second supports 

 the middle pair of legs and the anterior pair of the organs of flight, 

 and to the third are attached the posterior pair of legs and the pos- 

 terior pair of wings. A binary division of the thoracic segments has 

 been proposed, founded upon the nature of the organs of motion ; 

 thus the anterior of the three segments is the manitrunk of Kirby, the 

 collum of Knoch, and the corselet of Strauss ; whilst the two pos- 

 terior wing-bearing segments are united into the " segment alifere" 

 of Chabrier, the alitrunk of Kirby, the pectus of Knoch, and the 

 thorax of Strauss. The composition of each of the thoracic segments 

 (and indeed of every segment according to the views of Audouin) is 

 essentially similar, consisting of four dorsal subsegments, namely, the 

 Praescutum, Scutum, Scutellum, and Postscutellum; and the Paraptera, 

 Sternum, Episterna, and Epimera, which are lateral or ventral pieces. 

 In the Hymenoptera, Diptera, and Lepidoptera, the prothorax is 

 almost evanescent or reduced to a simple collar; but in the Coleo- 

 ptera, the pronotum (its upper surface) is the very large piece suc- 

 ceeding the head, and which has from the days of Linnaeus been 

 ordinarily but incorrectly termed the thorax, and its subsegments are 

 entirely confluent, this segment being destitute of wings ; indeed, it is 

 only in the prothorax of some Locusts that the dorsal subsegments of 

 the prothorax can be traced. But in the Mesonotimi and Meta- 

 notum (or dorsal parts of the meso- and metathorax) the subseg- 

 ments are much more conspicuous, indeed the scutellum of the 

 mesothorax was noticed by Linnaeus as one of the chief component 



