3°6 
THE TANGANYIKA P ROB LEM. 
swarms with medusae ; vast shoals of them, as I found, 
extending for miles and miles, and containing individuals of 
all sizes, but nearly all of them presenting manubriums 
which were covered with hundreds of minute developing 
buds. On the other hand, as the season advanced, more 
and more of the medusae encountered were not quite in this 
condition, and these distinguished individuals presented a 
Fig. 5. — Rather older asexual bud X sh showing lens break- 
ing through the endoderm lining the base of the gastric 
cavity. To the left there are to be seen on the outer surface 
of the folded manubrium a group of a succeeding generation 
of asexual buds. 
very curious appearance indeed, many being almost, if not 
quite, destitute of manubrium. By an examination of 
numbers of individuals as the season advanced, I was soon 
led to the conclusion that this amanubriate condition was 
produced by the animals actually shedding the whole of the 
outer portion of the manubrium wall during the process of 
casting off their innumerable buds. Others again, during 
this period, were found with well-developed manubriums 
