INTRODUCTION. 



and the inferior median cell, fig. 25, am and cm. In some genera, 

 the cross nerve between nerves 4 and 5 is obsolete, so that the 

 median cell is here open and passes into cell 4. There are also 



Fig. 25. 



21 



Tig-. 26. 



sometimes small inclosed cells at the median, called accessory cells, 

 which are either situated at the root of the secondaries, fig. 22, r, 

 or intrusive cells, as fig. 25, s, or appendicular cells, as fig. 25, x. 



In the family of Tineidce with lanceolate secondaries, the nerve 

 structure declines. The median cell is indistinct or entirely obso- 

 lete, for all the nerves arise either from the root or other nerves, 

 or lose themselves in the membrane in the vicinity of the cross 



- 27. 



Fig. 28. 



nerve. The number of nerves, especially in the secondaries, also 

 diminishes. 



In order to distinguish the wings lengthwise, they are divided 

 into three fields or areas, the basal area, figs. 1 and 20, ba, the 

 middle area, ma, and the limbal area, la. In many genera, these 

 areas or fields on the primaries are marked or distinguished by 

 simple, double or triple cross lines or narrow bands, which are 

 called, fig 20, sa, transverse anterior (extra basillaire) or posterior, 

 sp (ligne coudee). These transverse bands or streaks are most 

 distinct and common in the Noctuidce, fig. 20. In these, there is 

 in addition a cross line between the base and the anterior line, 

 which does not extend down to the interior margin, and which is 

 called the basal half line, sd (demi-ligne of the French); and ano- 

 ther conspicuous cross line between the posterior line and the limb, 

 called the undulate line, IT (ligne-subterminal). In the field or 

 area, between these two, there are often arrow-shaped spots, which 



