PROC. ENT. SOC. WASH., VOL. 23, NO. 6, JUNE, 1921 149 



mental character upon which our classification must rest, it does 

 not tell the whole story, nor is it alone always sufficient to deter- 

 mine natural groups. Characters of the pupa and larva and 

 genitalia give an added light and a fuller understanding. In 

 fact the seta arrangement in the larva is as fundamental as 

 the venation. As an independent basis for classification it en- 

 ables sure and accurate group definition and the results corre- 

 late with those obtained by venation. 



Genitalia on the other hand are subject to such extreme modi- 

 fications and the group characters are so subtle that unsupported 

 by other characters in the insect, they would not be a safe guide 

 except for specific differentiation; but as an additional factor in 

 the classification they are of considerable significance, enabling 

 clearer and sharper definition and finer division of families and 

 genera. 



For example, while the division between the families Tortri- 

 cidac and Olethreutidae has always been clearly recognized and 

 their species properly referred, no exact definition between them 

 has been possible on venation or other hitherto considered adult 

 characters. It is a curious coincidence that an attempt should 

 have been made to employ genitalia in the separation of these 

 very families by Fernald and Meyrick and unfortunate that 

 these authors should have hit upon a superficial character the 

 presence or absence of uncus which does not hold. 1 



The long standing confusion regarding the family Xylorictidae 

 and its present mistaken lumping with the family Stenomidae 

 could have been avoided by a consideration of the genitalia. The 

 two represent distinct geographical entities with but few 

 stragglers outside their respective continents, Australia and 

 America, and their genitalia in gross structure and detail (for 

 example the split hairs on the harpes in Stenomidae) at once 

 separate the two. 



The genus Setiostoma Zeller described as a Glyphipterygid 

 and always so considered on pterogostic characters is defi- 

 nitely proven by the genitalia to belong to the family Steno- 

 midae (not equal Xylorictidae Meyrick). This fact is fully 

 born out by a proper consideration of the venation though the 

 venation alone might be and has been otherwise interpreted. 



In the separation of genera the genitalia must be used with 

 extreme caution, but here also they throw an additional light 

 on the correlation of species and thereby enable a more natural 

 grouping and a sharper division. 



As a character for specific differentiation the genitalia are of 



f: "Uber den Genitalapparat von Rhopobota Naevana," Iris, 1908, pp. 

 304-329. 



Heinrich: "A Note on the Tortricid Genitalia," Proc. Ent. Soc. Wash., vol. 

 19, 1917, pp. 137-138. 



