100 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



few species have not reached as far as the majority in the 

 development towards the Lithocolletis ideal ; they have retained 

 a small unessential vein from the ancestral type, which the 

 main body of species have lost ; and a single species is slightly 

 in advance over the main body by having lost an extra vein. 

 Thus we have : 



LITHOCOLLETIS (Authors). 

 Porphyrosela Braun 



| 

 Phyllonorycter Hiibner Cameraria Chapman 



Cremastobombycia Braun 



Cylindrical larva 



Flat larva 



Allied Gracilariid stock 



It may be that these subdivisions of the cylindrical-larva 

 group are worthy of subgeneric rank ; I consider the differences 

 too trivial for generic use. It would be logical to include all the 

 species of both groups in one genus ; this at least would be a 

 natural group ; but to erect subgenera for two of the subdi- 

 visions of the one main branch and then include the other main 

 branch in the third subdivision is obviously unscientific. 



The best way is to recognize the two easily defined main 

 divisions of the group as good genera, for which the names 

 Phyllonorycter Hiibner* (type, rajclla Linne) and Cameraria 

 Chapmanf (type, gutti finite Ha Clemens) must be used. 



I have treated this comparatively unimportant case in some 

 detail, because it elucidates similar cases of much more far- 

 reaching consequences, in which I think the present classifica- 

 tion of the microlepidoptera weak, or rather, unnatural. 



We have been doing our classification too 'much horizontally, 

 so to say any twig on the entire phylogenic tree which has 

 reached a certain type of imaginal structure has been placed 

 in such or such a genus or family without sufficient regard for 

 its origin. This does not produce a natural system. 



In the above diagramatic phylogenic tree it is of course the 

 easiest to say that everything which has reached a certain 

 level A is to be considered a systematic entity and that what 



*Hiibner, Tentamen, 1806. 



fThe Entomologist, xxxv, p. 141, 1902. 



