388 



consisting of epipharynx and hypopharynx. Antenna 

 eleven segments. Palpi four segments. 



Simple eyes (ocelli) absent ; thus distinguished 

 from Bibionidae. Eyes in $ joined together (holoptic). 

 The facets on the upper part of the eye are the larger. 



Egg. Deposited in a compact layer on stones and 

 grass. Egg measures 0*40-0*18 mm. 



Larva. Twelve segments. On under side of 

 anterior portion is a subconical retractile process 

 crowned with bristles. Anal extremity bristly, with 

 three short retractile tentacles. 



Pupa. Has a respiratory tuft on each side of 

 thorax. Pupa has spines by which it anchors itself to 

 the cocoon. These can be found under small stones 

 in the shallows of sparkling brooks. Pupal stage about 

 five days. 



W.'.j of "Plilfloto-mus ^ 



Fig. 119 



(i) Genus Simulium. Body small, hump-backed, 

 with a hairy felt-work (tomentum). Head small. Palpi 

 four segments, the fourth composed of numerous 

 annuli ; larger in ? than in J . Antennae eleven 

 segments, narrowing to the tip, a little longer than the 

 head. Wings large. First, second, and third veins 

 dark, remainder pale. <? generally black, ? cinereous. 

 Eyes contiguous in $ (holoptic) remote in ? (di- 

 choptic). 



