388 
consisting of epipharynx and hypopharynx. Antenna 
eleven segments. Palpi four segments. 
Simple eyes (ocelli) absent; thus distinguished 
from Bibionidae. Eyes in S 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. 
Fig. 119 
(1) 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 2 than in S. Antennae eleven 
segments, narrowing to the tip, a little longer than the 
head. Wings large. First, second, and third veins 
dark, remainder pale. S generally black, 2 cinereous. 
Eyes contiguous in S (holoptic) remote in 2 (di- 
choptic). 
