larva living in rotten fungi. S. Niger, Deg. Curt. 609 (rugosus).

20. Cyrtida.

This unique group, till quite recently known as the Acrocerida, is also a limited and natural one, being allied to some genera of Bombylida. Small, soft, globular flies, the abdomen being apparently filled with air, splitting open with 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 gibbosus, 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. Empida.

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 ♂ 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 9, 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 coxæ shorter than femora.

Proboscis long: third longitudinal vein forked: Empina.

Proboscis short; third longitudinal vein simple.

Anal cell longer than lower basal cell: Hybotina. Anal cell shorter than lower basal cell: Ocydromina.

Anterior coxæ very prominent; as long as, or longer than, femora: Hemerodromina.

Anal cell absent: Tachydrominæ.

Hybotina.-Hybos grossipes, L., is a small shining black fly with black legs, the posterior femora being enlarged in the ♂. Flight slow; it usually hovers in swarms on summer evenings. Long 4 mm. Cyrtoma, Mg., inhabits trees and woods in summer. Empina.-Empis, L. The larva and pupa live in

the earth, the latter in some species being spined. About thirty species are British, appearing chiefly in 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 tibiæ, and very pale brown or quite clear wings; common; long 8-9 mm.

E. tessellata, 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 transverse 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 tibiæ; long 4-5 mm.

Hilara, Mg. Many species of this extensive genus are met with on summer evenings, swarming over

streams.

H. maura, 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 ♂. Ocydromina.-About six or eight species are

British.

Hemerodromina.-Hemerodromia, 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. Tachydromina.-Tachydromia, Mg., an extensive genus, is represented in Britain by about thirty species, occurring in marshy situations; their movements 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, Pl. J. 5. E. borealis, L., Curt. 18. Ragas unica, Wlk., Wlk. iii. 3. Clinocera stagnalis, Hal., Wlk. iii. 6.

22. Dolichopida.

About one hundred and sixty species of this family are indigenous. Two very excellent monographs on the genus Dolichopus, Latr., have been published by Stannius (1831), and Staeger (1842).

The Dolichopida are rather small flies, usually of a metallic green or bronze colour, with long, spiny legs, very brittle in character. The wings are generally clear, the abdomen usually conical, shining,

and shortly pubescent. Many species are common; they occur chiefly on hedges and in grass, on the stems of reeds, and plants of low growth. The abdomen at the tip curls inwards in the majority of the species.

Psilopus, a genus of delicate, long-legged flies; congregates in small groups in shady spots.

Dolichopus, Latr., found in marshy ground and long grass, in rank herbage and about overgrown pools; a few species occur on the sea-coast. Degeer has observed the transformations of D. ungulatus.

Dolichopus trivialis, Hal., metallic green; face above antennæ green, below whitish; antennæ black; wings pale grey; legs livid or pale yellow; tarsi black; tibiæ spiny; common; variable; long 4-5 mm. Poecilobothrus nobilitatus, L., brilliant metallic green; under-side of thorax with silvery-grey reflections; face silvery below, green above; antennæ, which are black; legs pale yellow; tips of posterior tibiæ, and all tarsi black; wings clear; a large brown streak near the tip extending from fore to hind border; not uncommon; long 5 mm.

Diaphoris, Mg., and Chrysotus, Mg., very small and uncommon flies, metallic in colour, occurring on trees in the hot sunshine.

Argyra, Mcq., conspicuous by the whitish pubescence on the abdomen in some of the species; generally distributed.

Argyra diaphana, F., thorax blackish; dorsum me. tallic green; abdomen greenish-black; sides of first two or three segments pale yellow, and from the second segment to the tip, with whitish tomentum ; face and antennæ black; wings pale grey; legs blackish-brown, tibiæ lighter; not

uncommon;

variable. The ground colour and markings of the abdomen resemble those of Homalomyia caniculata; long 6 mm.

Porphyrops, Mg., about twelve species-some not

uncommon.

Hydrophonis, Whlg. This, with Medeterus of Fisch, are carnivorous genera (Doubleday and Macquart both record having watched them devour small insects.) The former inhabits the surface of pools; the latter frequents dry, warm localities, and is conspicuous by its bulky proboscis.

Thinophilus, Whlbg., three species; rare; sea

coast.

Scellus notatus, F., metallic bronze; sides of thorax with whitish reflections; face brown or black; whitish below antennæ ; antennæ black; wings with brown streaks along the veins, and a distinct brown spot on fourth longitudinal vein near the tip; legs blackish; a few scattered spines; not rare; long 51-6 mm.

Campsicnemus, Wlk., found in damp grass, occuring during the greater part of the year. C. scambus is not rare.

The following plates are good:--Argyra leucocephala, Wlk. i. Pl. vii. 4. Medeterus diadema, Wlk. i. Pl. vii.

8. Psilopus Weidemanii, Wlk., i. Pl. vi. 1. Campsicnemus scambus, Wlk., i. Pl. vi. 6. Porphyrops elegantulus, Curt., 541. Scellus notatus (Hydrophorus), Curt., 162.

23. Lonchopterida.

A limited group of small active flies, inhabiting grassy marshes and such like habitats, being found during the greater part of the warm weather. About half a dozen species are British, two being tolerably common, L. lutea, Pz., the commonest, being yellowish-brown with black antennæ and eyes, a black spot on the vertex of the head and the centre of the front of the pronotum; a brownish-black vertical stripe on the abdomen (variable); a thin central brown line on the thorax, and dark tarsi. Lonchoptera lutea, Pz., Wlk., vol. i. Pl. viii. I,

24. Platypezida,

All the four European genera of this family are British, representing about a dozen species, all more or less uncommon, inhabiting woods, the larvæ living in fungi.

Van Roser has published his observations on P. boletina, Fall., the larva of which lives in rotten mushrooms, and resembles a seed. Westwood figures it in his "Class. Ins.,” vol. ii. Fig. 130-17. Walker illustrates P. picta, Mg., "Br. Dip." i. Pl. viii. I, and Callomyia elegans, Mg., Pl. viii. 3.

Curtis gives a good plate of Opetia lonchopteroides, Curt., in his "Br. Ent." 489; mostly shining black flies, about 4-5 mm. long.

Allied to both the Platypezida and Syrphide (to the latter, through the sub-family Bacchina). Three genera are European, two being British. They inhabit fields and woods, and are in the habit of hovering in the air; they are not difficult of determination, but none can be said to be common. They are larger than the Platypezida, and more stoutly built.

Discoidal cell present: Pipunculus, Latr. Discoidal cell absent: Chalarus, Wlk. Pipunculus pratorum, Fall., Curt. 757. Chalarus spurius, Fall., "Br. Dip." i. Pl. viii. 7.

26. Syrphida.

This extensive and well-known group is divided into several sub-families, and represented in Britain by over 200 species (about 1100 species are European).

As a rule the species of this family are flat-bodied,

Chrysotoxum, Mg.

Antennæ normal-shorter than head-deflexed.

Abdomen much retracted at basal segments:
Baccha, F.

Abdomen barely or not retracted at base.

Eyes pubescent; wings spotted.

Abdomen golden yellow: Chrysochlamys,
Rond.

Abdomen blackish blue: Leucozona, Sch.
Eyes bare; wings never marked.
Species yellow and black.

Abdomen elongated-longer than wings:
Sphærophoria, St. Farg.
Abdomen oblong or oval-shorter than
wings.

Anterior tibiæ in ♂ dilated; abdomen
oblong: Platychirus, St. Farg.
Anterior tibiæ never dilated; abdomen
oval: Syrphus,, F.
Species black or greenish-black.

Front rough or furrowed: Chrysogaster,
Mg.

Front smooth: Chilosia, Mg.

Syrphus, F. This, the commonest genus, is represented by about thirty-five rather closely allied species, all more or less resembling wasps. Abdomen bright yellow, with transverse black stripes; thorax yellowish, greyish, or livid; legs thin, yellow with black rings; wings usually clear; long about

7-9 mm. The commonest species are S. ribesii, L., corolla, F., pyrastri, L.; larva figured by Westwood, Class, Ins. ii. Fig. 130-21. Balteatus, Deg., Bouché has observed the metamorphoses of this species, and luniger, Mg. The larvae of this genus feed on Aphida.

Platychirus, St. Farg., an allied genus of about twelve British species, has a narrower abdomen, several species being common; about the length of, and closely resembling Syrphus. The venation in Syrphus, Platychirus, Chilosia, and Melanostoma is very similar. Mr. Verrall, in the "Ent. Mon. Mag.," gives some excellent notes on the British species of Platychirus.

Chilosia, Mg., a rather large genus of black flies, more or less pubescent, rather stoutly built; wings never marked, and generally grey or brown. Chiefly found in woods and meadows, and most of the species are more or less local; long about 8-10 mm, A continental authority (Professor F. Kowarz) has recently revised the majority of the European species.

Rhingia rostrata, L., a characteristic species; tawny brown, with a black head and thorax; tawny face produced in the form of a strong, long, pointed snout; wings pale grey; legs tawny; proboscis long and horny; common; long 7-8 mm. Reaumur found the larva in cow-dung.

Eristalis, Latr.-These are the typical "drone flies," several species being very common, the larvæ living in stagnant water.

E. tenax, L., is a brown fly, with grey or pale tawny marks on the abdomen; face clothed with short, pale yellow pubescence, with a strong, broad, central black line; legs brown, paler at the knees and tips; wings clear, or slightly brown at the base, foreborder, and towards the tip; thorax clothed with short thick tawny brown pubescence; abdomen very variable in colour, sometimes entirely black; very common everywhere; long 10-12 mm.

I once placed a lived in a glass-top box with a dead and it remained in côp. for about half an hour.

E. intricarius, L., abdomen thickly clothed with black hair, tip with whitish hair; base of the tibia pale yellow; wings clear; scutellum surrounded by thick yellow hair; thorax clothed with black hair; rather smaller, less common, and more local than tenax. The colour of the pubescence varies greatly, being sometimes nearly all yellow, or with a reddish tinge; long 8-9 mm.

E. arbustorum, L., a very common species, smaller than intricarius ; abdomen bare, tawny with, roughly speaking, two black triangular spots on it, their apices nearly touching; legs black and yellow; wings clear; thorax with greyish yellow pubesence; face with yellowish white hair; frontal stripe in black; long 8 mm. ; very common everywhere; variable.

Volucella bombylans, L., a large bee-like fly covered

with thick pubescence, which is yellow on the thorax, black at base of the abdomen, and whitish or reddish at the tip, and two yellow tufts of pubescence at the sides of the base of the abdomen; under side of thorax with thick black hair; face with yellow hair, and in with a central stripe of thick yellow hair; legs black; wings pale grey, brownish tinged along the fore border; very variable. There are two distinct varieties, both of which Miss E. Ormerod has bred from one batch of eggs; and Mr. Verrall possesses a series, showing every form of intermediate colouring; common; long 9-11 mm.

V. pellucens, L., a large black fly; bare; basal half of abdomen livid; legs black; wings nearly clear, with a large irregular blackish spot in the centre of the fore border, extending downwards half way across the wing; face yellow; slightly smaller than bombylans; common.

Helophilus pendulus, L., a yellow fly; bare; top of thorax black, with four yellow stripes; abdomen with transverse black markings; face yellow, with a central black line; legs black and yellow; posterior femora enlarged; wings clear; rather common; long 9-10.

Several other species of Helophilus are more or less common in Britain; mostly yellowish in colour, and allied to pendulus; known as "sun-flies," their habits being similar to those of Eristalis.

Xylota segnis, L.-Black, basal half of abdomen dull red; face with short whitish pubescence; legs black, with base of tibiæ yellow; wings grey or pale brown; posterior femora enlarged; long 8-9 mm. About six species of Xylota are British. The larva of Xylota lives in decayed wood,

Syritta pipicus, L., is a small and very common insect found everywhere, London included. Black, with the under side grey; face with thick greyish white pubescence, a small yellowish spot at each edge of posterior borders of the abdominal segments; legs black, marked with tawny or yellow; posterior femora much enlarged; wings quite clear; variable in size and markings. Larva lives in horse-dung; long 5-7 mm.

Criorhina oxyacantha, Mg., resembles a bee; covered with yellow pubescence, deepest in colour on the thorax ; face much produced; black, covered on upper side with thick yellow hair; legs all black or dark brown; wings pale grey, yellowish at the base, and with a black stripe extending half way across the wing from the centre of the fore border. The larva lives in river bank mud; long 12-13 mm.

Eumerus, Mg., a genus allied to Syritta, is represented by three species.

Chrysogaster, Mg., is a genus of metallic, dark, greenish-black flies, with rather dark wings; black legs, short pubescence; several species, all closely allied, are British; one of their characteristics is the grooved face; they appear chiefly in spring and summer on Ranunculi; long 6-7 mm.

Chrysotoxum, Mg.-Seven species are British. A genus of large, handsome, wasp-like flies, except that the base of the abdomen is not contracted; thorax black, with yellow side markings; face black, generally with a wide central black line; abdomen oval, convex, yellow with transverse black markings;. legs thin, principally yellow; wings unmarked, greyish; base tawny yellow; long 10-12 mm. Larva feeds on plant roots.

The Syrphida occasionally swarm in countless numbers, when several species are sometimes found forming part of the host. At Margate, in August, 1869, the following appeared in vast profusion during one day :-E. tenax, S. balteatus, and Sphærophoria taniatus.

Swammerdam and Reaumur have studied and illustrated their writings on the life-histories of several common species.

Over a thousand species are European. Sphegina clunipes, Fln., Wlk. i. Pl. x. 16. Syrphus pyrastri, L., Wlk. i. Pl. x. 12. Leucozona lucorrum, L., Curt. 753. Rhingia campestris, L., Curt. 182. Volucella inflata, F., Curt. 452. Sericomyia borealis, Fln.,. Walk. Pl. ix. 14. Syritta pipiens, L., Wlk. Pl. ix. 9. Criorhina oxyacantha, Mg., Wlk. Pl. ix. 12. Chrysotoxum bimaculatum, Curt. 853.

27. Conopida.

This group is a small one, allied to both the Syrphide and higher forms of Muscida. The species in the first division closely resemble wasps (Odynerus, &c.); the larvæ are parasitic on bees, Latreille having reared P. rufipes from living Bombida, whilst Westwood noted the abundance of O. atra on sandbanks in which several species of bees burrowed.

One or two authors have greatly multiplied both genera and species, nearly all their names being now sunk as synonyms. The eyes are wide apart in both sexes, the being distinguished by a ventral horny process towards the end of the abdomen. None of the species can be said to be common. Antennæ stylate; ocelli absent (Conopina).

First abdominal joint of normal width: Conops, L.
First and second abdominal joint much retracted: Phy-
socephala, Sch.

Antenna with a bristle; ocelli present (Myopina).

Proboscis bent only at the base: Zodion, Latr.
Proboscis bent at the base and at the middle.

Face much produced downwards below the eyes;
proboscis short: Myopa, F.

Face not much produced downwards below the: eyes; proboscis long: Oncomyia.

Conopina.-Conops flavipes, L., is black and yellow; face yellow, with a central black stripe; antennæ black; thorax black, with yellow spots on. shoulders; abdomen black, with two (g) or three (d) yellow bands; legs yellow and black; wings. greyish; fore border brownish; long 10 mm. is the most common species of the genus.

This

Phyrocephala rufipes, F.-Phyrocephala is distinguished from Conops by the first and second abdominal segment being much contracted; the legs

are thinner, and have frequently a twisted appearance. The colour of P. rufipes is brownish red; face yellowish, with a black central stripe; antennæ black; legs tawny brown, marked with black; wings pale grey, anterior portion pale brown almost to the tip; tip of abdomen covered with thin silvery-grey tomentum, and it varies in colour; long 10 mm.

Myopina.-Sicus ferrugineus, Scop.; rather common and widely distributed. Uniformly tawny; face broad-reddish-yellow; wings pale grey, tinged with tawny; long 6-8 mm.

Myopa testacea, L., is tawny; dorsum of thorax

28. Estrida.

Physocephala

The Estrida form a small but very interesting group, represented by eight British species. In the imago the mouth is obsolete, the venation more or less obscurely defined, and the alulæ large; eyes widely separated in both sexes. In the larval state they are parasitic, each species living on or in a different animal, the larva dropping to the earth when fully developed, and pupating in the ground.

In Gastrophilus equi, F., the lays her eggs in the mane of the horse, and on the animal licking it, the eggs pass into the stomach, where the larvæ emerge and develop, afterwards passing out with the dung, and pupating in the earth. The imago is a brown fly, with yellow and brown pubescence; the face is covered with yellow pubescence; the legs are thin, yellow, somewhat short; the wings grey, with a dull brown stripe in the centre; the abdomen has yellowish pubescence. Long 11-12 mm.

Oestris ovis, L. The lays her eggs on the nose of the sheep, the larvæ crawling thence into the head, where they attain their full size, afterwards descending the nostril, and assuming the pupa state in the ground.

It is a brownish-grey fly, with clear wings, large white alulæ, and yellowish-brown legs; long 9-10 mm. When attacked, the sheep cluster in a circle, Tholding their noses together close to the ground.

Hypoderma bovis, Deg., is parasitic on cattle, laying its eggs in the back, a tumour arising, from which when full grown the larvæ emerge. Black, pubescent; tip of abdomen with red pubescence; face and under side with grey pubescence; legs black; wings brown; long 12-14 mm.

ROSSENDALE RHIZOPODS.

No. 3.

NOW come to a genus of testaceous Rhizopods,

viz., Difflugia, so common, and so widely distributed, that every microscopist is more or less familiar with their arenaceous, box-like shells. Every pond, ditch, and bog is sure to furnish one or more species of this ubiquitous genus, if the sediment be carefully examined; and it is somewhat comical to see the box-like shells, especially the taller species, bobbing about among the Algae and broken-down organic detritus. The genus contains about twelve species-differences in form of shell or test, and in the character of the mouth, separating them. These species, however, are often connected by intermediate forms, and it is sometimes very difficult, and more rarely impossible, at the time, to say definitely to which species a given specimen may belong, as it may possess the characters of at least two species, in fairly-balanced proportions. They present themselves

Fig. 91.-Difflugia pyriformis. Fig. 92.-D. pyriformis.

as round, oval, pyriform, or in other ways elongated, box-like shells, made up of large and small sandgrains and diatom frustules (chiefly of the linear kind), separately or mixed in various proportions; in more than one species it is of chitinoid membrane, and especially is this the case in the forms from Sphagnum. Indeed, I believe that in all the species there is a chitinoid basis, even in those species in which nothing but sand-grains can be seen. They vary greatly in form and size, not only among themselves, but in the same species. I have seen a D. acuminata as large as the of an inch in height; other and rounder species are as small as the top of an inch in diameter; but from too of an inch may be considered as ordinary dimensions. The sarcode is occasionally coloured, more commonly green, and