LEPIDOPTERA. 



199 



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 „ m, th mit, 



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 

 are borne by the protho- 

 rax, and in many cases 

 are capable of consider- 

 able movement. 



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. 



"wwtwai^,*. The presence 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 

 Fig. 240.— Head of moth, showing .... - , . . , 



position of ocellus. 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 leucostigma. 



