BJBIO. 135 



fourth subclavate ; fourth shorter than the third ; fifth linear, longer 

 and much more slender than the fourth. Antennae nine-jointed, sub- 

 moniliform, porrect, short ; first and second joints nearly linear, pilose ; 

 third and following joints transverse ; ninth rounded. Thorax nearly 

 oval, very convex. Wings of moderate size ; costal vein ending at a 

 little in front of the tip of the wing ; mediastinal and subcostal veins 

 ending at bevond half the length of the wing ; the first very slight ; 

 radial ending at before two-thirds of the length; cubital proceeding 

 from the angle of the praebrachial transverse veinlet, ending at the tip 

 of the costal vein ; subapical forked before two-thirds of the length of 

 the wing, its fore fork curved ; prsebrachial emerging from the subanal 

 at one-third of the length of the wing, ending at an equal distance 

 between the subapical and the subanal ; anal not reaching the border ; 

 subaxillary imperfect ; areolets thirteen, the humeral, the radical, the 

 mediastinal, the radial, the cubital, the prsebrachial, the pobrachial, 

 which is much longer than the praebrachial, the subapical, three externo- 

 medial, the anal, and the axillary, the two latter being partly united ; 

 posterior margin forming an acute angle at full twice the length of the 

 humeral areolet from the base. Halteres long. Abdomen with nine 

 segments, much longer than the thorax. Legs stout, moderately long ; 

 femora and tibiae channelled ; tibiae with two apical spurs ; fore tibiae 

 with a long apical spine ; joints of the tarsi from the first to the fourth 

 successively decreasing in length ; fifth a little longer than the fourth ; 

 ungues and onychia distinct. Male. Body very hairy. Head large, broad. 

 Eyes very large, very hairy, connected above. Abdomen obtuse at the 

 tip ; hind tibiae clavate. Female. Body rather hairy. Head slender. 

 Eyes small, remote. Abdomen acuminated at the tip. Larva subter- 

 raneous, vermiform, cylindrical, furnished with twenty spiracles, and 

 with transverse rows of short hairs, which serve for locomotion. Head 

 furnished with two obtuse hooks. Pupa naked, enclosed in a smooth 

 oval cell ; its thorax very gibbose, with the rudimental wings and legs 

 very short. 



The species of Bibio are mostly vernal; they abound chiefly in 

 meadows, and occasionally appear in great numbers ; their larvae 

 feed on the roots of grass. The males, like other Nemocera, often 

 hover in the air, with their hind legs vertical. "The legs all 

 point backwards in flight, the long anterior pair forming an acute 

 angle with the body/' The species may be grouped thus : 

 a. Legs of the male and of the female wholly black. Species 1-4. 

 a a. Legs of the male and of the female partly red. 

 b. Femora of the male red. Species 5. 

 b b. Femora of the male black. 



c. Body of the male with black hairs. Species 6. 



c c. Head and thorax of the male with black hairs ; abdomen with 



pale hairs. Species 7, 8. 



c c c. Head of the male with black hairs ; thorax and abdomen 

 with pale hairs. Species 9. 



