3° 6 



THE TANGANYIKA PROBLEM. 



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 



