30 THE BUTTERFLIES OF THE 



of the median vein as the median venules or veinlets, 

 the branches of the subcostal as the subcostal venules 

 or veinlets, the branches from the cross-vein as the discal 

 venules or veinlets. The space through which these 

 venules pass is sometimes spoken of as the discal space, 

 or disk. The submedian and internal veins occupy the 

 area below the median, the latter being short and some- 

 times wanting. 



The arrangement of these veins — called by some 

 authors nerves and nervures — is of value in classification, 

 and they also serve to locate markings which rest either 

 near or upon them. When the wings are expanded 

 (and that is presumed to be the case in the following 

 descriptions of species and in the key), the front edge is 

 called the costa, the part next to the body the base, the 

 edge farthest from the body the outer or terminal margin, 

 the part opposite the costa the posterior or hind margin 

 (the inner margin of some authors). The angle between 

 the costa and the outer margin is called the apex ; the 

 one between the outer and hind margin may be known 

 as the posterior angle when applied to the fore wings. 

 The hind wings have the costa, outer margin, and apex 

 the same as the fore wings, the latter being sometimes 

 spoken of as the outer angle, but the part of the hind wing 

 next to the body is called the internal or inner margin, 

 and the angle at the end of this the anal angle. 



In Europe, and to some extent in this country, a 

 system of numbering the veins has been adopted. The 

 plan is to number them in order at their termination 

 along the margin of the wing, without regard to their 

 length. By this plan the one extending from the base 

 of the wing below the median would be called 1, the first 



