300 SYSTEMATIC ARRANGEMENT 



mum state of development, they are five in number. 

 The longitudinal one placed along the anterior 

 border of the wing, is usually called the costal 

 nervure : it was named by J urine, who first gave a 

 nomenclature to these parts, the radius, from a 

 notion that it was analogous to the bone so named 

 in vertebrate animals. For the most part this is the 

 strongest nervure in the wing, as it forms the ante- 

 rior edge when that organ is extended, and has, 

 therefore, to cut through the air during flight. The 

 nervure next to this, and running parallel with it, 

 is the sub- costal nervure, the cubitus of Jurine. 

 Both these terminate in an opaque expansion on the 

 anterior border of the wing not far from the middle, 

 which is called the stigma, a term which has been 

 appropriated to a totally different part of structure, 

 but is now in too general use in its twofold sense 

 to be disturbed. The sub-costal gives off, a little 

 before its origin, a third nervure, which runs almost 

 in a direct line towards the centre of the wing, and, 

 at a longer or shorter distance from its commence- 

 ment, describes numerous zigzag lines; this it has 

 been proposed to call the medial nervure. Beyond 

 this a pretty wide area usually intervenes, which is 

 bounded posteriorly by a nervure running somewhat 

 obliquely towards the centre of the hinder border, 

 which has received the name of sub-medial. The 

 last is more slender than the rest, and has been 

 very appropriately called the anal nervure. 



The nervures just described are always more or 

 less united bv transverse and recurrent nervures, 



