476 



DIPT ERA 



CHAP. 



r -V * \ 



rli K N 



it is a curious fact that the same sexual distinction of colour 

 reappears in various parts of the world England, America, India, 

 and New Zealand ; moreover, this occurs in genera that are by 

 no means closely allied, although allied species frequently have 

 concolorous sexes. The eyes of the males are well worth study, 



there being a very large upper portion, and, 

 abruptly separated from this, a smaller, differ- 

 ently faceted lower portion, practically a 

 separate eye ; though so largely developed the 

 upper eye is in some cases so hairy that it 

 must greatly interfere with the formation 

 of a continuous picture. Carriere con- 

 siders that the small lower eye of the male 

 corresponds to the whole eye of the female. 

 The larvae of Bilno (Fig. 225) are caterpillar- 

 like in form, have a horny head, well de- 

 veloped, biting mouth-organs, and spine-like 

 processes on the body-segments. They are 

 certified by good authorities 1 to possess the ex- 

 tremely unusual number often pairs of spiracles; 

 a larva found at Cambridge, which we refer to 

 Bibio (Fig. 225) has nine pairs of moderate 

 spiracles, as well as a large terminal pair 

 separated from the others by a segment without 

 spiracles. The genus Dilopli-us is closely 

 allied to Bilrio, the larvae of which (and those 

 of Bibionidae in general) are believed to feed 

 on vegetable substances ; the parasitism of 

 Dilophus mil gar is on the larva of a rnoth, Epino- 

 FIG. 225. Larva of tia (Ckaetoptrio) hypericana, as recorded by 

 Cam- Meade, 2 must therefore be an exceptional case. 

 In the genus Scatopse there is a very im- 

 portant point to be cleared up as to the larval respiratory 

 system ; it is said by Dufour and Perris 8 to be amphipneustic ; 

 there are, however, nine projections on each side of the body that 

 were considered by Bouche, and probably with good reason, to 



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 f 4 



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bridge. x 5. 



1 Osten Sackcn, Berlin, cnt. Zcitscltr. xxxvii. 1892, p. 450. 



- Kiilininili/ijist,, xiv. 1881, p. 287. This obsm atiun has never, we believe, been 

 confirmed. 



:; Ann. Soc. cut. France (2) v. 1847, p. 46. 



