JIYMENOPTERA. 247 



upon the characteristics acquired by the larvae in fam- 

 ilies which provide their young with food by laying 

 their eggs in plants, in the bodies of other animals, 

 or that rear them in nests, as is customary among 

 the more specialized forms of Hymenoptera Aculeata. 

 The larvae under these conditions would naturally and 

 inevitably lose the useless legs, and even in some cases 

 more or less of the mouth parts whenever these be- 

 came also useless, and the soft, fleshy, grub-like form 

 would replace the more active caterpillar-like larva. 



Other evidence of the convergence of these two 

 orders is not wanting. Walters, after extensive inves- 

 tigations, has shown that true biting mandibles exist in 

 some of the more generaHzed forms of the moths, 

 being especially well developed and furnished with 

 teeth in Micropteryx, and also shows that in this 

 genus the mouth parts can be compared part for 

 part with those of the Tenthredinidae (saw-flies), 

 concluding that the latter approximate most closely 

 to the generalized ^ lower ") forms of the Lepidop- 

 tera than the insects of any other order.^ 



1 " Beitrage sur Morphologic des Schmetterlinge," Zeitschrift 

 f. Medicin u, N'atnrwissenshaft, Jena, 1885, XVIII., p. 799. 



