LEPIDOPTERA. 



199 



iir, inriii, 



cell lying immediately behind vein III is cell III, and that lying 

 immediately behind vein V is cell V. 



Accessory Cells. — In many genera the branches of vein III of the 

 fore wings anastomose 

 so as to form one or 

 more cells beyond the 

 apex of the discal cells 

 (Fig. 239, a.c^ ; these 

 are the accessory cells. 



Discal Vein. — The 

 cross vein at the outer 

 end of the discal cell is 

 termed the discal vein 

 (Fig. 239, d.v:). 



Patagia. — At the 

 base of each fore wing 

 there is a scale-like ap- 

 pendage ; these are the 

 patagia. The patagia 

 correspond to the tegulse 

 of the Hymenoptera and 

 the elytra of the Cole- 

 optera. 



In descriptions of 

 Lepidoptera reference is 

 often made to the palpi. 

 These form the double beak-like projection which extends forward 

 from the lower surface of the head. In most Lepidoptera only the 

 labial palpi are well developed ; but in some of the more generalized 

 forms the maxillary palpi are also present. 



■swwawas^jsas;,^^^ The prcscncc or absence of ocelli 



is a character which is sometimes of 

 considerable importance. These or- 

 gans are situated, one on each side, 

 above the compound eye and near its 

 margin (Fig. 240). But it requires some 

 skill to find them when they are present, 

 on account of the long scales clothing the head. 



The Phylogeny of the Lepidoptera. — Since the general acceptance 

 of the theory of evolution — that is, the theory that the higher animals 

 and plants have been developed from lower ones — it has become evi- 

 dent that the only sure basis for classification is a knowledge of the 



Fig. 239. — Wings of Notolophus leucostigvia. 



Fig. 240. — Head of moth, showing 

 position of ocellus. 



