152 CATALOGUE OF NORTH AMERICAN DIPTERA. 



have come to a practical unanimity in accepting certain principles of nomen- 

 clature which radically change the generic names used by Osten Sacken, who 

 followed Loew. The change hinges on the application of the name Cecidomyia 

 (disregarding for the time being the new genera w'hich have naturally come into 

 existence), and will be found fully discussed in the following papers: 



Karsch, Revision der Gallmiicken, jNIunster, 1878, 10-20. 



Osten Sacken, Catalogue, 215, note i, 1878. 



RiJBSAAMEN, Berl. Ent. Zeitsch., xxxvii, 324-327, 1892. 



KiEFFER, Annales Soc. Ent. France, 1900, 436. 



Osten Sacken, Ent. Mo. Mag., 1901, 40-43. 

 The practical effect of the changes adopted by Karsch, Riibsaamen and Kieffer 

 is to apply the name Cecidomyia to the Diplosis of Osten Sacken's Catalogue, 

 and to divide up his Cecidomyia between Rhahdophaga and Dasyneura. As 

 nearly all the species in the family were referred to Cecidomyia and Diplosis in 

 Osten Sacken's Catalogue, the adoption of the changed nomenclature will leave 

 few members of the family in the same genera to which Osten Sacken referred 

 them. 



Realizing the immense practical disadvantage of such an overturning of names, 

 I should have been well content to let the problems of nomenclature lie in abey- 

 ance; but they have been already threshed out in Europe, and the conclusions 

 reached and put in use there cannot be ignored. 



After much consideration, I can find no better course to follow than to adopt 

 the generic distribution of Kertesz, in his Catalogus Dipterorum, vol. 11. Not 

 having much knowledge of the family myself, and not being able to consult an 

 American authority on it, I have carried out this plan. I take occasion to re- 

 mark, however, that Osten Sacken thoroughly disapproves of the changes, and 

 has given, in the last reference above, his reasons for his views. 



Some of the species still included under Cecidomyia doubtless belong to other 

 established genera, but are not yet sufficiently described to allow of a positive 

 reference ; in fact, many of the species need further study, and at best the present 

 scheme must be considerably modified by more thorough investigation. No 

 family of the Diptera offers greater inducements to a worker who will patiently 

 carry on the biological and systematic study of it conjointly. 



The status of those names which have been applied to larvae and galls only, iji 

 to pupae, larvse and galls, or even to galls alone, need not be settled at the present 

 time. I have placed all such names in a division by themselves. My opinion is 

 that when the adult is at last described, the same old specific name should be 

 used, unless impracticable, but that thenceforth the description of the adult should 

 be regarded as the real description of the species. Meanwhile, it is very con- 

 venient, and thoroughly in accord with the objects of nomenclature, that the pro- 

 visional name should stand. 



A few species described since Kertesz have been added, in harmony with his 

 general distribution. 



Cross-references have not been thought necessary, considering the small size 

 of the family. 



The European literature is voluminous ; KiefTer gives over 800 references. His 

 Monographic des Cecidomyides d'Europe et d'Algerie, in Annales Soc. Ent. 

 France, 1900, 181-472, 30 plates, is indispensable to any student of the family. 

 I add here only a few references. 



CoMSTOCK, Dept. Agric. Rept., 1880, 270, 271, list of references on para- 

 sitic and inquilinous species. 



Brauer, Zweifl. d. Kaiserl. Mus., iii, 1883, 20 and 53, references to descrip- 

 tions of larvae. 



