DIPTEBA. 



53 



ing quickly and suddenly away a yard or two, again taking up 

 the same immovable position, and in each of these movements 

 turning the head to the opposite way from that in which they are 

 going. This naturalist is certain that on these occasions they are 

 watching for the females, which they dart upon. When they 

 have succeeded in doing so, they rise so high as to be out of 

 sight. 



To this group belongs the genus Tabanus. 



The first species we shall mention, Tabanus autumnalis (Fig. 

 33), a common species, is eight or nine lines in length, and of 



Fig. 33. Tabanus autumnalis. Fig. 34. Chrysops csecutiens. 



blackish colour. The palpi, the face, and the forehead are grey ; 

 the antennae black ; the thorax grey, striped with brown ; the 

 abdomen spotted with yellow, the legs of a yellowish white, and 

 the outer edge of the wings brown. 



Another species ( Tabanus bovinus) is twelve lines in length, and 

 of a blackish brown. The palpi, the face, and the forehead are 

 yellow, the antennae black, with a whitish base; the thorax, covered 

 with yellow hair, is striped with black ; the posterior edge of the 

 segments of the abdomen pale yellow ; the legs yellowish, with 



