3 °° 
THE TANGANYIKA TROBLEM. 
when floating in the water and seen from above it, only 
the edge of the opaque manubrium and the adjacent 
circle of tentacles being visible. The radial symmetry 
is extremely simple, there are often in the adult only four 
short canals leading from the base of the gastric cavity. The 
animal is provided with remarkable marginal sense organs 
described by Mr. Gunther, and which are curiously 
like those of the only other fresh-water jelly fish about 
which anything definite is known, namely, Limnocodium 
sozuerbii. * 
Some of the tentacles are long and hollow, adhering at 
their bases for some distance to the outer surface of the 
disc, and these longer tentacles are symmetrically arranged 
between shorter tentacles in such a manner that several 
series of regularly alternating lengths are always to be found 
on a single specimen. 
The animal forms asexual buds upon the manubrium, 
and at certain seasons distinct male and female individuals 
present clusters of sexual elements in the same position. 
Up to the time of my own examination of Tanganyika 
nothing was known of the life history of this jelly fish, but I 
have been able to acquire a considerable body of information 
respecting this, and I am strongly inclined to believe that 
the organism, like some of the marine narcro medusae, is 
altogether without a hydroid phase. The following are, 
however, the facts : — I was able to observe the medusae in 
Tanganyika throughout the months of April to November, 
but it should be borne in mind that Tanganyika is so long 
that the climate differs in the south from that of the north of 
* This is the form which mysteriously appeared and disappeared in the Victoria 
Regia tanks in the Botanical Society’s Gardens at Regent’s Park. It was described 
by Professor Allman and Professor Ray Lankester. It may possibly have been introduced 
among estuarine water plants from the rivers of South America ; but it has never been 
rediscovered there, and it has now gone. 
