DIPTEEA. 67 



fore-legs, and their noses nearly in contact with the ground. 

 When these poor beasts are in the open country, they are observed 

 assembled with their nostrils against each other and very near 

 the ground, so that those which occupy the outside are alone 

 exposed. The Cephalcemia ovis (Fig. 49) has a less hairy head, 



; 



Fig. 49. Cephalsomia ovis. 



but larger in proportion to the size of its body, than the Gad-fly 

 (CEstrus equi). Its face is reddish, its forehead brown with pur- 

 ple bars, its eyes of a dark and changing green, its antennae black, 

 its thorax sometimes grey, sometimes brown, bristling with small 

 black tubercles, the abdomen white, spotted with brown or black, 

 and the wings hyaline. 



The Cephalcemia ((Estrus) ovis is to be found in Europe, Arabia, 

 Persia, and in the East Indies. It lays its eggs on the edges of 

 the animal's nostrils, and the larva lives in the frontal and maxil- 

 lary sinuses. It is a whitish worm, having a black transverse 

 band on each of its segments. Its head is armed with two horny 

 black hooks, parallel, and capable of being moved up and down 

 and laterally. Underneath, each segment of the body has several 

 rows of tubercles of nearly spherical form, surmounted by small 

 bristles having reddish points, and all of them bent backwards. 

 " These points," says M. Joly, " probably serve to facilitate the 



F 2 



