HA RD WICKE' S SCIENCE- G OSSIP. 



127 



larva living in rotten fungi. S. Niger, Deg. Curt. 

 609 {nigosiis). 



20. Cyrtidcc. 



This unique group, till quite recently known as the 

 AcroccridiZ, is also a limited and natural one, being 

 allied to some genera of Botnhylida:. Small, soft, 

 globular flies, the abdomen being apparently filled 

 with air, splitting open Avith the least touch ; head 

 nearly all eye ; thorax very convex ; venation very 

 indistinct, and confined principally to the upper 

 portion of the wing ; legs very short ; sluggish in 

 nature ; found on tree trunks and flowers, or floating 

 about in the breeze on calm, sunny days ; long 

 4-5 mm, 



Oncodes gibbos^is, L., is selected by a species of 

 Crabro, which burrows in wood, as the food for its 

 young. 



Only two genera are British, each represented by 

 a single species. 



Third longitudinal vein forked : Paracrocera, Mik. 

 Third longitudinal vein simple : Oncodes, Latr. 



Paracrocera globulus, Pz., Wlk. PL i, 16. 



21, Empidie. 



About 160 species of this extensive family are 

 British. Their habits are very various, they 

 frequenting woods, ditches, fields, and the banks of 

 streams, some having the power of running over the 

 surface of the water. Head small ; body attenuated ; 

 legs long and slender ; posterior femora in <f in some 

 genera much enlarged. 



Some inhabit the coast, a few frequent flowers, 

 running with great swiftness over the leaves and 

 herbage. Many species are common, some abundant, 

 often for a few days only, and while swarming, fly 

 backwards and forwards in streams, moving as by a 

 common impulse. 



The venation varies in the several genera ; mostly 

 carnivorous (especially the ? , the ^ often feeding on 

 the juices of plants), small Diptera, and Ephemerida 

 appearing to be their chief prey. 



Westwood illustrates the larva of one or two 

 species. Five sub-families are recognised, all being 

 represented in Britain, 



Anal cell present. 



Anterior coxae shorter than femora. 



Proboscis long: third longitudinal vein forked: Em- 



pincE. 

 Proboscis short ; third longitudinal vein simple. 



Anal cell longer than lower basal cell : HybotincE. 

 Anal cell shorter than lower basal cell : Ocy- 

 dromirue. 

 Anterior coxae very prominent ; as long as, or longer than, 

 femora : H emerodroniiiue . 

 Anal cell absent : Tackydromina:. 



Hybotincs. — Hybos grossipes, L., is a small shining 

 black fly with black legs, the posterior femora being 

 enlarged in the d". Flight slow; it usually hovers 

 in swarms on summer evenings. Long 4J mm, 

 Cyrtoma, Mg,, inhabits trees and woods in summer. 



Empincc. — Empis, L. The larva and pupa live in 



the earth, the latter in some species being spined. 

 About thirty species are British, appearing chiefly iu 

 the spring ; the 9 are very voracious. 



E. livida, L., is a long brown fly, with three 

 longitudinal 'black stripes on the thorax ; long pale 

 tawny legs, with black tips to tarsi and tibice, and 

 very pale brown or quite clear wings ; common ; 

 long 8-9 mm, 



E. iessellata, F,, is allied to the above ; rather 

 stouter and larger, legs darker brown ; thorax with 

 three black stripes ; abdomen marked with a light 

 spot in the centre of, and joined to a light posterior 

 border to, each segment ; wings brown ; long 9 mm. 

 Macquart observed one species {O. opaca, F.) emerge 

 from the pupa, 



Rhamphomyia, Mg., allied to Empis ; apical trans- 

 verse nervure wanting ; twenty species British, their 

 habits being similar to those of Empis. 



Pachymeria femorata, F,, is a small black fly with 

 pale brown wings and black stigma ; black legs with 

 the two posterior pairs with dense black fringe on 

 femora and tibice ; long 4-5 mm. 



Hilara, Mg. Many species of this extensive genus 

 are met with on summer evenings, swarming over 

 streams. 



H. maiira, F., is a small shining black fly with 

 black legs and pale grey wings ; black along the fore 

 border and with black stigma, I could have taken 

 ten or twelve thousand specimens of this species one 

 day at Staines, where it swarmed over a shallow 

 stream. It is very common ; long 4 mm. The 

 species (twenty are British) are closely allied. The 

 anterior tarsi in many species are dilated in the ^ . 



Ocydromince. — About six or eight species are 

 British. 



Heiiierodromijicc. — Heinerodromia, Mg., inhabits 

 grass, shrubs, and moist situations ; their flight is 

 slow; their fore-legs enlarged ; long 3-5 mm. 



Clinocera, Mg., a genus of slenderly-built flies, of 

 which we have nine species ; inhabits moist localities, 



Tachydro7nini2. — Tachydromia, Mg., an extensive 

 genus, is represented in Britain by about thirty 

 species, occurring in marshy situations ; their move- 

 ments are very agile, running swiftly over the leaves. 

 This species are widely distributed, 



H. grossipes, L., Curt. 661 (pilipes). E. livida^ 

 L., Curt. Farm insects, PI, J, 5, E. borealis, L., 

 Curt, 18, Ragas unica, Wlk,, Wlk. iii. 3. Clinocera 

 stag7talis, Hal., Wlk, iii. 6, 



22, Dolichopidce. 



About one hundred and sixty species of this family 

 are indigenous. Two very excellent monographs on 

 the genus Dolichopiis, Latr., have been published by 

 Stannius (1831), and Staeger (1S42). 



The Dolichopidcs are rather small flies, usually of 

 a metallic green or bronze colour, with long, spiny 

 legs, very brittle in character. The wings are 

 o-enerally clear, the abdomen usually conical, shining^ 



