197 



ON AN UNDETERMINED OAK-GALL. 



BT ELEANOR A. ORMEBOD. 



especially on the spines. 



The accompanying figure (1, natural size, 2, section, 3, magnified) 



is of a small gall, which I found last summer on a fragment of a leaf 



^ amongst a number of oak-sprays 



gathered in the neighbourhood of 



Isleworth. 



The gall is about a quarter of 

 an inch in diameter, irregularly 

 spherical, about two-thirds of it 

 above the upper surface of the leaf 

 thickly beset with spines, for the 

 most pai't simple, but in some cases 

 branched (as at 4), the colour yel- 

 lowish-green, with a mixture of rose, 

 Internally, the gall is single-chambered, with 

 a hard, woody wall, about a quarter of the diameter of the gall in 

 thickness. 



On examination (when the time had passed for probable develop- 

 ment of the gall- insect), the only tenant proved to be a whitish larva, 

 dead, and too much distorted for complete identification, but from the 

 presence of strong jaws, legs, and pro-legs, certainly not either dip- 

 terous or cynipideous. This larva, w^hether parasitic or otherwise 

 (being the only fragment of a clue to the nature of the gall-maker), 

 I have placed with the coloured drawing of the gall in the collection 

 of British galls in Museum 2, at the Eoyal Glardens, Kew, and one 

 portion of the bisected gall is in the hands of Dr. Friedrich Thomas, 

 of Ohrdruf, Grotha (the well-known gall-observer) for reference. The 

 gall was unknown both to him and the English gall-observers who 

 have seen it. 



Dr. G. Mayr, in his "Mitteleuropaischen Eichengallen," p. 33, and 

 plate iv, fig. 44, gives a sketch of the gall of " Cynips gemmea" Gir., 

 which, except in the spines of the O. geminea being shorter than in the 

 specimen figured above, bears much resemblance to it, but of these he 

 merely says, " I refer, with regard to this doubtful kind, to the de- 

 scription in Dr. Gii'aud's ' Signalements,' and give only a drawing from 

 a typical specimen in the Imperial Zoological Collection." 



My great difficulty in any identification of this very well marked 

 species arises from not noticing it at the time of gathering. I was 

 making a collection of oak-galls, and put the sprays together in a box, 



