HARDWICKE'S SCIENCE-GOSSIP. 



105 



Chrysopila aitratus, F., and aureus, Mg., are black 

 flies, smaller than Leptis, with clear wings and dark 

 brown stigma ; common ; long 7 mm. 



Atherix Ibis, F., is a rare species, occasionally 

 found- in swarms, the 9 2 clinging to one another 

 at the end of a branch, depositing their eggs, and 

 dying immediately afterwards ; the mass gradually 

 enlarging as fresh flies settle on it, and assuming a 

 pear shape. 



L. scolopacea, L., Wlk, i. PI. ii. 6. Z. notata, 

 Mg., Curt. 705, {Heyschami). C. aureus, Mg., 

 Curt. 713. A. Ibis, F., Curt. 26. 



16. Asilidcs. 



These flies are large, powerful, carnivorous insects, 

 especially the gi forming an extensive, natural 



Fig. ■jZ.—Tabanus, L. 



Fig. •]().— BombyHttj, L. 



Fig. So.— Pacrocera, Mik. 



group, being very abundant in warm countries, the 

 species there attaining very large size. 



R. Desvoidy saw a species of Dasypogon with an 

 Apis in its mouth. 



- Flight powerful, accompanied by a loud hum. 

 They frequent woods, pastures, and dry, sandy 

 situations, the larvae living on plant roots. 



The metamorphoses of most species are unknown. 

 The venation is distinct. 



Westwood figures larva and pupa of Asilus 

 crabroniformis, L., in his Class. " Ins.," Vol. ii.. 

 Fig. 129. 



Four sub-families, and 14 genera, representing 

 about 20 species, are British. 



Marginal cell open. 



No onychia to tarsi: Leptogastrina. 



Onychia present : Dasypo^oninie. 

 Marginal cell closed. 



Third antennal joint non stylate : Laphrince. 



Third antennal joint stylate : Asilincz. 



LeptogastrituB. — Leptogaster cylindrica, Deg. Easily 

 recognised by its extremely attenuated abdomen, 

 the short wings, and absence of onychia ; long 9-10 

 mm. 



Dasypogonina:. — Dioctria rujipes, Deg., is a more 

 stoutly-built black fly, and with pale grey wings, the 

 two anterior pairs of legs being reddish ; long 1 1 mm. 

 The six British species of Dioctria are easily recog- 

 nised, and appear to be most common in Sussex. 



Laphrina:, — Two species British ; both uncommon, 

 (I have taken L. marginata on nut in Kent.) 



Asilittcz. — Asilus crabroniformis,^ L., is a large, 

 pubescent, tawny-brown fly, with the apical half of 



Fig. %i.— Leptis, F. 



Fig. S2.— Anthrax, Scop. 



Fig. 83. — Xylophasus, Mg. 



the abdomen yellow ; tawny-brown legs, spiny and 

 hairy ; yellow wings with brown border. Its flight 

 is peculiar, settling on the ground every few yards. 

 Linne says it attacks cattle ; long 18-20 mm. 

 Dysmachus trigonus, Mg., a smaller, greyish species, 

 pubescent and spiny, and Machimus atricapillus, Fin., 

 an allied species, with the legs prettily marked v/ith 

 tawny rings, are both tolerably common. 



A. crabrotiiformis, L., Wlk. i. PI. ii. 2. L. 

 cylindrica, Deg., Mg., Sys. Bes. iii. PI. xii. 16 

 (tipuloides). Laphria margitiata, L., Curt. 94. 

 Isopogon brevirostris, Mg., Curt. 153. Pamponerus 

 germanicus, L., Curt. 46. 



( To be continued. ) 



PROFESSOR WEISMANN'S THEORY OF 

 HEREDITY. 



ABOUT a year ago I began the first of a series of 

 papers on this subject, but was obliged to leave 

 off owing to the pressure of other work. I had been 

 struck by the fact that there had been only one or 

 two casual references in the pages of Science- 

 Gossip to a subject which was more than any other 



