OF TABANUS DIT^NIATUS AND TABANUS KINGI. 



269 



The female fly deposits her eggs in a rounded mass on a rock rising sheer 

 from tlie water (fig. 5), generally slightly overhanging, and from 6 inches 

 to 15 inches above water level. Rocks chosen for this purpose overhang- 

 comparatively deep pools — from 18 inches upwards — in which the water 

 moves but slowly. Such rocks occur only every here and there ; in the 

 mile or so of stream searched by the writer, only three rocks bearing traces 



I'ig. 4. — View of Klior Aibat, Ai]glo-Ej:yptian Sudan ; 'ooking up-stream. 



of having been used by this Tabanid for ])urposes of ovipositing were found. 

 On one of them were the remains of several hundred egg-masses lining a 

 small crack in the face of the rock from 2 ft. to 3| ft. above the water level. 

 As none of the fresh eog-masses found were situated more than 15 inches 

 above water level, these old masses had probably been deposited when that 

 level was higher. Altogether seven females were taken in the act of 

 ovipositing, and several more seen. No particular lime of the day seems 



