NATURAL HISTORY SOCIETY OF GLASGOW. Ill 



two very distinct forms, differing very considerably from each 

 other; one form being met with in the spring, this brood 

 occasionally producing males, although in the proportion of one 

 or two males to hundreds of females ; the second form occurring 

 in the autumn, and exclusively composed of females. Without 

 offering any opinion as to the other dimorphic form, Mr Cameron 

 remarked that the specimen which he exhibited could not be 

 placed in any of the modern genera, and that a new genus would 

 require to be formed for its reception — this, indeed, having been 

 already done by Reinhard, without that naturalist having seen 

 the insect. He likewise stated his conviction that it was ex- 

 tremely doubtful if the two so-called dimorphic forms described 

 by Walsh pertained to the same species. 



PAPERS READ. 



I. — On the AsjjJiondyliae of the Glasgow district. By Mr 



Francis G-. Binnie. 



Those abnormal swellings and outgrowths found upon plants of 

 all orders, and familiarly known as " galls," present one of the 

 most interesting fields for study that it is possible to select. The 

 majority of these diseased growths are the work of insects, 

 among which two families stand pre-eminent as gall-makers — viz., 

 the Cynipidae among the Hymenoptera, and the Cecidomyidae 

 among the Diptera. 



The productions and habits of the latter family — the Ceci- 

 domyidae, or Gall-midges — I have made it my object to 

 investigate, and have already got together a considerable amount 

 of material, which I trust may furnish matter for various papers 

 before this Society, and which will probably embrace several new 

 species. 



I have selected the genus AsjyJioiidi/lia, not because I have 

 much that is new to advance, but from the very interesting habits 

 of the species composing it, and from the well-marked characters 

 which distinguish it from the other genera of the family — ^'iz., 

 the absence of distinct whorls of hairs on the pubescent, cylindric, 

 and sessile joints of the antennae. Some of the largest species of 

 the group are to be found in this genus. The pupa is provided 

 with two projecting tooth-like processes at its anterior end, to 

 assist it in forcing its way through the tissues of the enclosing 

 cell when about to assume the perfect state. 



