HARDWJCKE'S SCIENCE-GOSSIP. 



53 



there unmistakably, leading to the conclusion that 

 the two are as closely allied as are \^QgC7tera in which 

 they are respectively placed by modern authors, but 

 not more so. 



The present moss may have been overlooked in 

 mistake for C. fontinaloidcs, but if a number of 

 specimens of the latter from different localities be 

 compared together, the leaves, while varying a good 

 deal in width, termination of the nerve, and also 

 slightly in the size of the cells, will be found to be 

 always more or less acute in general outline (Figs. 32 

 and 33 d), only the actual point sometimes obtuse, and 

 strongly twisted when dry. In C. riparuis the leaves 

 are obtuse, and either rounded, the nerve disappear- 

 ing at or below the apex (Fig. 34 e) ; or there is a 

 small slightly recurved apiculus (Fig. 35 f). The basal 

 cells are more elongated and slightly narrower. 



Pending the appearance of an authoritative de- 

 scription of the species, the foregoing remarks may be 

 of some slight assistance to the increasing circle of 

 students in this fascinating branch of botany who may 

 now make search, and not without hopes of success. 



W. P. Hamilton. 



Shreivsbury. 



AN INTRODUCTION TO THE STUDY OF 

 BRITISH DIPTERA. 



By E. Brunetti. 



[Continued /roin p. 39.] 



HE Diptera are divided into four primary 

 groups : — 



T 



Legs at juncture with thorax contiguous : Proboscidea. 

 Antennae of many joints (at least six) : Nematocera. 

 Antennae of only three distinct joints. 



Posterior veins of wing, branched : Brachycera. 

 Posterior veins of wing, simple : Hypocera. 

 Legs at juncture with thorax wide apart: Eproboscidea. 



NEMATOCERA. 



The characters of the Nematocera may be sum- 

 marised as follows. Body, delicately elongated, legs 

 usually long and slender, antenna of many joints, 

 flexible ; veins in wing numerous, alulae small, ocelli 

 usually present, anal cell in wing usually open. 



The venation in many genera varies in the 

 relative lengths of some of the veins and their 

 respective positions. 



llesonotum with a distinct vertical furrow : TipuUdce. 

 Mesonotum without such furrow. 

 Ocelli present (two or three). 



Discoidal cell complete : Rhyphida. 

 Discoidal cell absent. 



Antennae half length of thorax. Pronotum brought 



forward, conspicuous : Bibionidce. 

 Antennae at least as long as thorax. Pronotum 

 normal, conspicuous : Mycetophilida. 

 Ocelli absent. 



Costal vein barely reaching top of wing. 



Antennae shorter than thorax. Wings, broad ; 

 tibiae and metatarsus broad, compressed. Siviu- 

 lidce. 

 Antennae as long as or longer than thorax. Wings 

 narrow, librae and metatarsus slender, cylindrical : 

 Chironomidce. 



Costal vein attenuated round posterior margin of wing : 

 At most six posterior wing cells : Cecidotnyidce. 

 At least more than six cells. 



Wings ovate ; tip pointed : Psydiodida. 



Wings oblong ; tip rounded : Ctilicida. 



1. Cecidomyidcs. 



Winnertz has elaborately monographed some of 

 the European genera of thi:; group, having devoted 

 twenty-five years to the study of this family. The 

 larvoe are oval, fleshy grubs, feeding on various parts 

 of plants ; many form galls, and some live in rotten 

 wood. The pupse resemble the imago, but are of 

 course wingless. 



Degeer and others have observed the trans- 

 formations of some of the species. The imagos are 

 elegant and delicate small flies, about seventy or 

 eighty species at least being British, though Walker 

 introduces double this number. 



Schiner recognises two sub-families. 



Fourth longitudinal vein absent : Cecidomyinae. 

 Fourth longitudinal vein present : Lestreminae. 



Cecidoviyia destructor. Say., is the " Hessian fly," 

 which in its larval stage does such extensive damage 

 to the wheat. It is not rare on the continent, 

 devastating at times whole districts, but has seldom 

 been met with in England. It is of a brownish grey 

 colour, with clear wings, elongated abdomen, and 

 long, thin, black legs. 



Diplosis tritici, Kirby, is known as the " wheat 

 midge." 



The neuration of Diplosis resembles that of 

 Cecidomyia, except that the vein nmning towards the 

 top of the wing is usually straight. 



Some other enemies of the agriculturist are, 

 C. brassiciS, Winn., feeding on rape pods. C.pyri, 

 Bouche, feeding on pear trees. D. centralis, Winn., 

 feeding on beech. 



Westwood figures the larva of D. pint, Deg., in his 

 "Class. Ins.," vol. ii. Fig. 125-6, and the pupa in 

 Fig. 125-7. D. veriia. Curt., Curt. 178. D. tritici, 

 Kirby, Curt. "Farm. Ins.," PI. i. 8. 



2. Mycetophilida:. 



The Mycetophilidie are small, delicate flies, re- 

 sembling the CecidomyidiE. Many of the genera are 

 easily recognised by the difference in venation and 

 the presence of spines on the legs, both of which are 

 good generic characteristics. The larvce live as a 

 rule in fungi or rotten wood. 



Antenna; as long or longer than body : lilacrocera, Pz. 

 Antennae much shorter than body. 



Terminal joint of palpi elongated : Plafyura, Mg. 

 Terminal joint of palpi short. 



Discoidal cell present : Sciophila, Mg. 

 No discoidal cell : Mycetophila, Mg. 



The four principal genera may be separated as 

 follows : — 



Sciara Thonm, L., is black, with long thin legs and 

 dark brown wings ; long \\ mm.* The larvae of this 



* Twenty-five millimetres make one inch. 



