290 
THE STUDY OF INSECTS. 
three-branched with them, whereas it appears four-branched 
in the Drepanidse (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 Oreta 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 pr olonged into a more 
* We class the Drepanidse among the Frenulum-conscrvers, although 
many of them hpw* lost the fienulum. 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 Geometnds. 
