GALL APHIDS OF THE ELM. 195 



1. The fate of the migrants of Schizoneiira americana, the 

 relation of this species to rileyi. 



2. The complete life cycle of Tetraneiira gramims. 



3. The complete life cycle of Colopha xthnicola. 



4. The relation of Colopha iilmicola and Tetraneiira (colo- 

 phoidea) gramims whether distinct species or dimorphic forms 

 of the same. 



5. The fate of the migrants of Pemphigus idmifusus, and 

 alternate host. 



6. The fate of the migrants of Tetraneiira nlmisaccnli and 

 alternate host. 



7. The relation of the American species to the correspond- 

 iv'g European species. 



It is with some hesitation that I present this group of aphids 

 with so much still not ascertained concerning them. Yet the 

 well-nigh hopeless mixups in the records of these species would 

 need to be straightened if possible. 



This initial step I have earnestly attempted. The previously 

 existing records, in many instances entirely unrelated as they 

 stand, are correlated in this present paper so that they are pre- 

 sented as a unit (of a scrapbook nature it is true) in order that 

 certain previous errors need not be repeated. The original 

 descriptions of all the species have been quoted verbatim, as 

 these are for the most part no longer available and a reference 

 to them is necessary. Some entirely new data, for the most 

 part slight, I have been able to add to each of the old species 

 considered, but the paper is very largely compiled as will be 

 seen by the liberal quantity of quotation marks. 



Even so much order in the existing chaotic records of these 

 few species as is here given would have been impossible except 

 for the generous aid which I have received. In this connec- 

 tion I wish especially to thank Mr. J. T. Monell, who has gone 

 carefully over the Colopha-Tetranciira situation so familiar to 

 him, and sent me profuse notes and extracts and lent me aphid 

 mounts most valuable for study, and I wish also cordially to 

 thank Professor Oestlund, Mr. F. A. Sirrine and Mr. J. J. 

 Davis, who have given me specimens and other aid most ser- 

 viceable in the present study. 



