290 



THE STUDY OF INSECTS. 



three-branched with them, whereas it appears four-branched 

 in the Drepanidae (Fig. 346). 



Although the humeral angle of the hind wings is greatly- 

 developed in these moths, some of them retain the frenulum. 



Fig. 346. — Wings of Or eta rosea. 



Fig. 347. — Wings of Platypteryx arcuata 



When the frenulum is present it is borne at the end of a 

 long thickened portion of the wing, so that it is at a con- 

 siderable distance from the point where the wing is attached 

 to the body (Fig. 347).^ 



The larvae are remarkable in having the anal prolegs 

 rudimentary, and the caudal segment prolonged into a more 



* We class the Drepanidae among the Frenulum-conservers, although 

 many of them have lost the frenulum. Among the true Frenulum-losers the 

 loss of the frenulum occurs while the race is still in a very generalized con- 

 dition, no trace of a frenulum being found among these insects except a rudi- 

 ment in the most generalized forms {Bombyx, Cicinnus). In the Drepanidae, 

 however, the frenulum is retained by very highly specialized forms. There is 

 a striking similarity in this respect between this family and the more 

 specialized Geometrids. 



