THE THORAX. 97 



are called AREOLETS (areolte), or CELLS (cellules, Jurine) ; and those 

 lying close to the marginal rib are called MARGINAL AREOLETS (areolee 

 marginales, PL XV. d, d) ; Jurine's, cellulce radiales ; those succeeding 

 to them, and formed by the postcosta and its branches, SUBMARGINAL 

 AREOLETS (ctreoltB submarginales, PL XV. e, e) ; cellulce cubitales of 

 Jurine. The transverse veins which branch from the longitudinal 

 nervures of the main stems, are called the CONNECTING VEINS (venae 

 anastomosis), or nervi recurrentes of Jurine. The areolets seated 

 at the end of the wing, and, sometimes not quite closed, are called 

 IMPERFECT (areolce imperfects, PL XV. J\ f), or cellules incom- 

 pletce of Jurine. The APPENDED CELL (cellula appendicea) of the 

 same author is a small, almost triangular areolet, situated at the apex 

 of the wing, which is formed by the furcate division of the vein spring- 

 ing from the stigma (in many genera of the Tent.hrcdonodea ; for 

 example, Perga, &c.). 



The space behind the second principal vein of the wing is its third 

 and last chief areolet, Avhich, in many cases (Hymenopterd), is ante- 

 riorly limited by a peculiar, slight vein, originating near the second 

 principal one ; and this areolet extends to about the middle of the 

 margin of the posterior wing. Several other veins and areolets (nervi 

 et cellula; brachiales, Jurine) are found within this space, which, as 

 they do not vary much in large groups, are consequently of less 

 importance for the determination of genera. 



In the membranous wings we also rind the same distribution into 

 three chief areolets which we have already indicated in the tegmina, 

 and we here distinguish them, with Kirby, as the MARGINAL AREOLET 

 (area costalis sive marginalis), CENTRAL AREOLET (area discoidalis s. 

 intermedia), and POSTERIOR AREOLET (area analis s. posterior). In 

 repose, during which the wings lie parallely upon the body, the poste- 

 rior areolet passes beneath the central one, turning upon its limitary 

 vein, like a door upon its hinge. In those orders, however, in which we 

 meet with elytra, or an analogous structure, the inferior wings are folded 

 in several directions. Thus, in the beetles, the whole apex of the wing 

 is very generally folded from the stigma back towards the base, or the 

 whole wing, from this point, folds itself like a fan (Forficiihi) , or this 

 plication originates from the base of the wing, according to the direction 

 of the radiating veins (Orthoptera}. 



The preceding general description treats chiefly of the anterior wings; 



H 



