MEMBRANACEOUS WINGS. 279 



Adjectives derived from these words are employed in de- 

 scribing lepidopterous and other insects. Thus we have such 

 words as maculated, fasciated, ocellated, &c. 



In the caddice flies, the wings are clothed with fine hairs, 

 whence the name of the order given to them by Kirby, 

 Trichoptera ; the wdngs of the gnat are also beautifully or- 

 namented with scales along the nerves of the wing. These 

 organs, in a general sense, are of an elongated triangular 

 form, the longest side being the exterior, or anterior, mar- 

 gin ; the opposite angle is the posterior, or internal, angle ; 

 the side between the base of the wing and this angle, is the 

 basal margin ; or, in the posterior wings, the anal margin ; 

 the other side is named the apical, or terminal, margin. 

 There is, however, the greatest diversity in the shape of the 

 wings, especially the posterior pair in the Lepidoptera j some 

 are notched, and many terminated by one or more long tails. 

 A small group of moths have been termed Plumes, from the 

 wings being divided into numerous feathers, the divisions 

 extending to the base of the wing ; some are five-plumed, 

 and others twenty-plumed. 



Adjoining the external margin of the wings, at some dis- 

 tance beyond their middle, a callous point is to be observed, 

 formed by the union of the nervures of this anterior or 

 costal margin, which is termed the stigma. 



In the orders Hymenoptera and Diptera the form of the 

 cells, originating in the nervures arising from the stigma, has 

 been much employed in distinguishing the various groups of 

 insects. That it is, in certain families, highly important, can- 

 not be doubted ; but we must not rely implicitly upon it as an 

 absolute character, since many groups, having very different 

 habits, and varying in other important characters, are identi- 

 cal in the neuration of their wings. The credit of having 

 selected these variations in the form of the cells, as afford- 



