112 Mr. J. Hardy on Excrescences from Mites. 



of the sloe, and found them likewise to be nests of apparently 

 the same species of Acarus. 



The alternate blisters along the sides of the alder leaf, and 

 occasionally found on that of the birch, gave the same result. 

 The species on the alder is probably different. The old mite 

 accompanying them is a mere point, and is well distinguished by 

 two or three squarish brown spots near the tip of the abdomen. 



The leaf of the Salix aurita offers not less than four different 

 galls; one large and smooth, occasioned by a black saw-fly 

 (Linn. Fn. Suec. 2301) ; two caused by the larva? of unknown 

 species of gall-midge [Cecidomyia) ; and a fourth minute purple 

 one, which is very abundant, and is analogous to those occurring 

 on the sloe and bird-cherry. The last, like them, contains only 

 young mites. 



Another locality for mites I find in some round bud-like pro- 

 ductions on the twigs of hazel. From green they become yellowish, 

 and then wither. The larva is white; as is the accompanying mite. 



A rough, pale-green, or purplish, fungus-like gall, which 

 opens from the underside of the leaf, is abundant on the foliage 

 of the alder in some of our deans. This is also a nursery of 

 young Acari. 



A conspicuous yellow gall near the summits of the stalks of 

 Galium verum growing on the sea-coast is also owing to mites. 

 The round fleshy galls of this plant are caused by the larvae of a 

 Cecidomyia. 



Colonies of young mites distort the leaves of Galium Aparine, 

 Lotus co'rniculatus, Polygala vulgaris and Campanula rotundi- 

 folia, by causing them to assume fantastic shapes, to become 

 discoloured, to thicken, or their margins to roll inwards. The 

 foliage of Galium Aparine is also affected in this manner from 

 the presence of the larvae of Psylla velutina of Foerster (Verhand. 

 Natur. Vereins. Preuss. Rheinlande, 1848, p. 87) ; which ap- 

 pears not to differ from Ps. Galii of the same author. This Psylla 

 produces similar effects on Galium palustre and G. uliginosum ; 

 and it lives likewise upon the leaves of Comarum palustre. 



The hoary, rounded, woolly tufts, so abundant in some places 

 at the summit of the shoots of the wild thyme, are also the pro- 

 duction of a crowd of young mites, as was first ascertained by 

 Loew (Dipterologische Beitr. iv. 24). Lightfoot (Flora Scot. i. 

 318) attributes them to a Chermes (Psylla) ; and Bremi thought 

 they were owing to the larvae of a gall-midge. The two Bauhins 

 considered plants in this condition a3 a distinct species; the 

 Serpillum vulgar e, minus, capitulis lanuginosis, C. Bauhini, Pi- 

 nax 220; S. vulgar e, capitulis tomentaceis, candicantibus, J. Bau- 

 hini, Hist. Plant, iii. 269. Tournefort, however, conjectured 

 that such appearances were owing to the irritation occasioned by 



