v.L'o.] on.-, 



district. In s]iite (if this abuiidance, however, I loiit^ searclied in vain 

 for the hirva and pupa, and only hist spring was rewarded bj^ finding a 

 few specimens. The habits of the larva and pupa would seem to be 

 very different from those of the other British species : they occur amon^ 

 thick vegetation (such as Glyceria and Tt/2)ha), never in the open. 

 This difference in habit is no doubt sufficient to account for the diffi- 

 culty in detecting them ; it is impossible to see them in the watei' 

 among the weeds. Structiu-ally both larva and pupa are very similar 

 to those of the next species, tlie chief difference being that the pair of 

 flattened bristles in front of the labrum on the under side of the head 

 a)'e much longer and narrower in C. pallidus, and have a smooth instead 

 of a serrated edge. Zetterstedt's JErioptera nyhlaei is apparently an 

 overlooked synonym of this species. 



Chaoborus crystallinus (De G.) {Oorethra phimicornis F.). — 

 A|)art from C. pallidus, I believe there is only one variable European 

 species of this genus. If this is so, the species must take De Geer's 

 name, which is the older. There is certainlj^ a striking contrast between 

 Uie darkest sjiecimens (var. fusca Staeg.), which are almost entirely 

 black, and the lightest, which are mainly yellow ; and it must also be 

 admitted that the extreme forms cannot usually be found at the same 

 time and place ; nevertheless, every gradation in colour can be 

 found ])etween the dark and the light forms, and though there are slight 

 differences in the hypoin'gia, these seem to vary in the same continuous 

 manner as the coloration. The amount of hair on the body and the 

 lH)sition of the cross- veins are also subject to the same indefinite variation. 

 Weseuberg-Lund (Mindeskrift for Japetus Steenstrup, 1914, No. xxxiv) 

 figures two forms of the larva and pupa, differing in the shape of the 

 ])re-labral spines, the respiratory horns, etc. ; but he also concluded that 

 he was dealing only with two forms of one species. 



Mochlonyx cidlciformis (De G.). — There are two European species 

 of this genus, one as yet undescribed ; but there can be little doubt that 

 our species is the one described by De Geer, and that M. ve.hitinus and 

 M. ejfuetiis are synonyms. Theobald was mistaken in his use of the 

 name culiciformis for one of the varieties of C. crystaUinus. Coquillett 

 (and those, such as Brunetti, who follow him) argue that since at 

 the first introduction of the genus Goretlira the only species mentioned 

 as belonging to it was " Tipula culiciformis De G.," which is a Moch- 

 lonyx, therefore Goretlira must be used in place of Moclilonyx, leaving 

 the group which has till recently been called Goretlira to be designated 

 by another name {Ghaohorus or Sai/omyia). These authors, however, 



2 X 



