1871.) 99 
Under such a mode of life the occurrence of some variation would 
not have been wonderful ; but, as I said before, the mountain insect 
and the pine one appear to be absolutely identical. 
Braemar, July. 
ON A CECIDOMYIA FORMING GALLS ON PTERIS AQUILINA. 
BY ALBERT MULLER, F.L.S. 
While the list given by Bremi (Beitrag zu einer Monographie der 
Gallmiicken, p. 62) shows that almost every family of plants fur- 
nishes sustenance to the larve of gall-midges, the ferns have hitherto 
been conspicuous by their absence from the list ; and for this very reason 
I have generally neglected their examination, acting on the erroneous 
notion that, if others found nothing, it was of no use for me to go over 
barren ground. So thoroughly had this error biassed my mind, that 
when, in 1867, my late friend, Mr. Armistead, of Leeds, sent to me 
specimens of rolled leaflets of the frond of the common bracken, with- 
out a trace of insect life, I was willing to call the roller anything 
rather than a Cecidomyia. Hence I only alluded to these productions 
in the “ Zoologist,” 1868, p. 1201, as follows: ‘“ Leaflets discoloured, 
“ either reddish or black, rolled up or otherwise distorted. ‘Are very 
“common here, Allonby, Cumberland.” W. A. in litt. August 9th, 
rel867.” 
But, since then, Filices have been examined by me one very possible 
occasion, and discoveries by others, to which I shall allude on their com- 
pletion, have lately increased my interest in the work ; and the reward 
has come. A stroll up to Shirley on Sunday last to a favourite spot of 
mine, near the Archbishop’s palings, will be fixed in my memory as 
being the occasion of finding reddish, fourteen-jointed larve of a Ceci- 
domyia, each snugly ensconced in the rolled and laid down leaflets of 
fronds of Pteris aqguilina. Often, the majority of the leaflets of a frond 
are thus tenanted each by one larva. The affected leaflet is at first 
neatly folded, or laid down lengthways on the under-side of the 
leaf, in which state it is pale green; subsequently it becomes a cigar- 
shaped roll of reddish colour, and at last it resembles nothing so much 
as a black pudding in miniature. The latter stage signifies that the 
larva has left it to undergo its metamorphosis underground; at all 
events, I have examined scores of these black rolls without meeting any 
pupal skins. To the best of my knowledge, no gall-midge has as yet 
‘een detected on the bracken ; and, although I anticipate that some sys- 
