The manubrium is absent altogether in the fresh-water medusa Limnocnida, in which the diameter of the mouth exceeds half that of the umbrella; on the other hand, the manubrium may attain a great length, owing to the centre of the sub-umbrella with the stomach being drawn into it, as it were, to form a long proboscis, as in Geryonia.
The sense-organs of the two fresh-water medusae Limnocodium and Limnocnida are peculiar and of rather doubtful nature '(see' E.
Limnocnida tanganyicae was discovered first in Lake Tanganyika, but has since been discovered also in Lake Victoria and in the river Niger.
" On the Freshwater Medusa Limnocnida tanganicae" Budgett Memorial Volume (Cambridge, 1908, pp. 471-482, p1.
Another fresh-water form is Limnocnida tanganyicae, discovered first in lake Tanganyika, and now known to occur also in the Victoria Nyanza and in the Niger.