3oo THE TANGANYIKA PROBLEM. 



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. Glinther, and which are curiously 

 like those of the only other fresh-water jelly fish about 

 which anything definite is known, namely, Limnocodium 

 sowerbii. # 



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 

 Kegia 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. 



