OF WASHINGTON, VOLUME XV, 1913. 87 



the group. With a view to the determination of this point, series 

 of specimens (in each case numbering over ten and in some cases 

 one hundred) representing the following species and genera have 

 been studied: Ephedrus incompletus; E. caUfornicus; Praon colora- 

 densis; P. simulans; P. occidentalis; Aphidius nigripes; A. poly- 

 gonaphis; A. pinaphidis; A. ribis; A. phorodontis; and Lysiphlebus 

 teslaceipes. In not a single one of these species was there found a 

 similar variation. On the contrary the maxillary palpi of species 

 of Ephedrus, Praon and Aphidius so far as indicated by the species 

 studied seem to be constantly four-segmented, while in Lysiphlebus 

 there are never more than three segments. The relative length 

 of the segments does often vary slightly and in one or two instances 

 specimens were found in which the segmentation appeared to be 

 incomplete but in no instance was there found so remarkable a 

 condition as in Diaeretus rapce. 



In discussing this paper Mr. Rohwer remarked on the variation 

 in the number of joints of the palpi of sawflies and stated that 

 within the genus Diprion he had found both symmetrical and asym- 

 metrical variation of five to six joints of the maxillary palpi. 



Under the heading of short notes the following communications 

 were presented. 



Mr. Rohwer called attention to the paper by A. Cosens 

 entitled "A Contribution to the Morphology and Biology of Insect 

 Galls," which appeared in the Transactions of the Canadian Insti- 

 tute, volume ix, 1912, pp. 297-387, pis. 1-13. This publication 

 deals with galls primarily from the botanical standpoint, but a 

 number of very interesting observations were made which should 

 become available to all entomologists interested in the study of 

 galls. 



In Mr. Cosens' work he has discovered a number of new species 

 and in the genus Pontania has been able to distinguish striking mor- 

 phological differences between the galls of closely allied species. 

 Mr. Cosens proves that the gall is produced by an enzyme, and 

 also that the gall can be produced if the stimulus is not applied to 

 the cambium layer. He also proves that certain inquilines in 

 "Cynipid galls also possess the gall-producing power but to a less 

 extent than the real producer;" and the "gall producing stimulus 

 renders the protoplasm of the host more active and awakens in it 



