THE TANGANYIKA PROBLEM. 
3 01 
the Lake. In the south there is a long dry season lasting 
from May to September, then a short wet season lasting for 
some two or three weeks, then a spell of fine weather which 
usually continues till about the end of November, when the 
great rains begin, and these finally terminate in a succession 
of heavy thunderstorms and furious nocturnal gales during 
the early days of May. In the north, that is in latitude 3 0 30' 
south, the seasons are more equal ; the September rains 
begin sooner and last longer, while the long rains of the 
south are proportionately shortened, so that in this portion 
of the lake we really experience the true climate of the 
equator, where there are two short wet seasons and two 
short dry seasons, the rains occurring whenever the sun 
passes overhead on its way north and south. 
The jelly fishes, however, do not differ in the phase of 
their life cycle in different parts of the lake, and conse- 
quently it is really incorrect to say that their metamorphosis 
corresponds in any way directly with the seasons. 
Fig. 2. — Living sexual adult of the Tanganyika 
medusa, showing the character of the manu- 
brium. 
