OF WASHINGTON. 261 



these were examined and it was found that the pedicel had 

 become shorter and stouter, while the anterior or buried end had 

 greatly increased, the exposed portion being now half empty of 

 its contents. Five days later, April 2yth, the young leaves had 

 formed from these same marked buds and the eggs were still in 

 position, but mostly empty, and when removed and closely 

 examined it was found that under the epidermis and below the 

 base of the exposed egg-shell there had formed a soft, colorless, 

 globular body, having a yellowish streak internally. This body, 

 probably the first larval stage, is easily detached from the leaf, 

 but no movement could be discerned and the thread-like pedicel 

 had separated from it and disappeared. 



So far, there is no trace of a gall or swelling to be seen, 

 although the affected leaves appear more or less crumpled or 

 distorted. May 4th the same leaves were again examined and 

 the young galls had already formed, appearing as slight thicken 

 ings of the leaf, but scarcely elevated or prominent. The spot 

 where the egg had been inserted forms a minute depression or 

 hollow in the leaf, with the colorless and shrivelled egg-shell still 

 in position, the cavity thus formed being in an oblique direction 

 to the surface of the leaf. The cell or cells in each gall are re 

 moved from the egg-shells about twice the length of these last, 

 but for which there would be little trace as to where the egg en 

 tered ; they are ovoid or rounded, and each contains a perfect 

 larva, semitransparent or colorless, with a brownish ventral spot. 

 Most of the galls contain three to five cells. 



From now on, the formation of the gall is rapid, the substance 

 of the young gall being very juicy and succulent and of a yellow 

 ish color, its outer margin or edge being pale pinkish. On May 

 nth the galls were nearly full grown and proved to be Calli- 

 rhytis ftitilis O. S., but no flies were reared until the middle of 

 June, and from this time until the last of the month flies in both 

 sexes were continually bred. A number of interesting subsequent 

 observations were made upon this interesting species, but have 

 no especial bearing on this communication. I ought, however, 

 to state that Mr. H. F. Bassett (Psyche, Vol. 5, pp. 235-8, Dec., 

 1889) has described what is, apparently, the same insect as Cal- 

 lirhytis radicis, which he reared from a series of blister-like 

 cavities in the bark of the root of Quercus alba, and identified 

 with the fly which he had himself observed ovipositing in 

 the buds of the same oak and producing the gall which gives 

 forth Callirhytis futilis Osten Sacken. There is consequently 

 some confusion as to the actual relations of this sexual generation, 

 and either an error as to determination on the part of Mr. Bassett 

 or else an erroneous record of rearing on the part of Mr. Ash- 

 mead. I have adopted the former as the more probable. There 



