I24 NORTH AMERICAN DIPTERA. 



never ending permutations of palpal and antennal joints, 

 are repeatedly used and according to his view are wholly 

 homoplastic characters, while it is seriously to be con- 

 sidered whether many of them are not of real genetic 

 origin, and consequently untenable in their subdivision al 

 and repeated uses. Older writers had recognized many, 

 if not most of these characters, but had refrained from 

 using them. 



In other words, I consider the present classification 

 offered by Kieffer as largely artificial and consequently 

 not permanent. But the table will call the attention of 

 the student to many minor characters which he would 

 otherwise be very apt to overlook. 



I do not accept the contention of Karsch, with which I 

 have long been familiar, that the names Cecidomyia and 

 Diplosis should be differently applied or abandoned. 

 Nor can I agree with Professor Aldrich that these changes 

 have been threshed out in Europe. I can find no writer 

 whose opinion is authoritative who has accepted them, 

 nor did Kieffer. On the contrary Osten Sackeu, whose 

 opinion I value more than that of any other recent 

 writer, has steadily opposed not only these changes, 

 but the apparently unnecessary reduplication of the gen- 

 era, for it must be remembered that Kieffer alone has 

 proposed and adopted about fifty new 'genera'. Hendel, 

 in reply to Osten Sacken's objections, has said that gen- 

 era exist in nature, and that all we have to do is to 

 recognize them — a remarkable declaration from a nat- 

 uralist of the twentieth century. I suppose he would 

 permit 'Nature' to occasionally revise its genera a la De 

 Vries! While it is true that the typical species of Meigen's 

 genus Cecidomyia is not included in that genus as accept- 

 ed by Loew and in this work, but is included under 

 Diplosis, it is also true that rigid rules of priority can not 

 be extended to the works of many of the early writers. If 



