HARD WICKE'S SCIENCE-G OSSIF. 



131 



are thinner, and have frequently a twisted appearance. 

 The colour of F. rufipcs is brownish red ; face 

 yellowish, with a black central stripe ; antennae 

 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. 



Myopinic. — Sicusfentigitiais, Scop.; rather common 

 and widely distributed. Uniformly tawny ; face 

 broad — reddish-yellow ; wings pale grey, tinged 

 with tawny ; long 6-8 mm. 



Nyopa iestacca, L. , is tawny ; dorsum of thorax 

 black, with greyish reflections ; wings pale tawny 

 grey ; internal transverse vein clouded ; under side 

 of face white ; pubescent ; rather common, and 

 generally distributed ; long 5-7 mm. 



M. biiccata, L., an allied and rather common 

 species, has pale brownish marks on the wings, giving 

 them a mottled appearance, and the transverse veins 

 are not distinctly clouded. Stomoxysy a genus of 

 Muscidir, has erroneously been included in this 

 family. 



Conops fiavipes, L., Panz. Ixx. 21. Physocephala 

 rufipes, F., Wlk. i. PI. x. 18. 



28. CEstridco. 



The (Estridit 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 imago the mouth is obsolete, the venation more or 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 alulae 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 9 lays her eggs in 

 the mine of the horse, and on the animal licking it, 

 the eggs pass into the stomach, where the lai-vae 

 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 g lays her eggs on the nose of 

 the sheep, the larvae crawling thence into the head, 

 where they attain their full size, afterwards descend- 

 ing the nostril, and assuming the pupa state in the 

 ground. 



It is a brownish-grey fly, with clear wings, large 

 white alulce, and yellowish-brown legs; long 9-10 

 mm. "When attacked, the sheep cluster in a circle, 

 liolding 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 larvae emerge. Black, 

 pubescent ; tip of abdomen with red pubescence ; 

 face and under side with grey pubescence ; legs 

 black ; wings brown ; long 12-14 mm. 



One or two other species are British, but are very 

 rare. Clark's essay on "Bots" is a splendid mono- 

 graph, splendidly illustrated. It is impossible to breed 

 the flies, as the larvos die on removal from its host. 

 They are very swift on the wing ; the larva; are 

 popularly known as "warbles," and the perfect 

 insects as "bot-flies." 



ROSSENDALE RHIZOPODS. 

 No. 3. 



I 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 Algse 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 inter- 

 mediate 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. gi. — Difflugia pyriformis. Fig. 92. — D. pyriformis. 



as round, oval, pyriform, or in|other ways elongated, 

 box-like shells, made up of large and small sand- 

 grains 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 Jin 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 them- 

 selves, but in the same species. I have seen a D. 

 acuminata as large as the j'j of an inch in height ; 

 other and rounder species are as small as the ^^^ of an 

 inch in diameter ; but from ^ to 5^ of an inch may 

 be considered as ordinary dimensions. The sarcode 

 is occasionally coloured, more commonly green, and 



