212 ROBERT PAYNE BIGELOW ON 



pouches (and hence, according to Goette, five eighths of the peripheral digestive tract of 

 the medusa) is of ectodermal origin. On page 550 of her paper she speaks of only the 

 roof, i. e., the lining of the oral side, of these pouches as formed from oesophageal ecto- 

 derm, and her sections bear out this view. 



The foregoing brief summary of the present state of knowledge regarding the early 

 stages in the development of the sexually produced scyphistoma will serve as an 

 introduction to what is to follow. Mention of the work of others upon the later stages 

 will be made when we come to the corresponding periods in the development of 

 Cassiopea xamachana. 



The Formation of the Bud. In 1841 Sars described the budding of scyphistomas 

 that were supposed to belong to a species of either Aurelia or Cyanea. The buds, accord- 

 ing to this account, may grow out directly from the main part of the body of the larva, 

 or they may be produced on stolons extending outward from the foot. In either case, 

 several buds may be formed, apparently in various positions on the scyphistoma at one 

 time. The figures show the buds attached to the parent and provided with a well- 

 developed crown of tentacles at the distal end. Agassiz ('60) found a similar process of 

 budding to occur occasionally in Aurelia. Goette ('87) has confirmed these observations, 

 and has found that the larvae of Cotylorhiza tuberculata also produce buds. 



In Cotylorhiza the bud is formed as an outgrowth from the body of the scyphistoma ; 

 and as it grows it gradually approaches the shape of its parent, but its relative position is 

 just the reverse of what Sars found ; for the distal end forms the stem, and the proximal 

 end begins to flatten, out into a circumoral disc. In this condition the bud is set free, and 

 swims about, rotating on its long axis, with its distal end forward. The moiith is formed 

 at the point where the constriction finally separates the bud from its parent, and the larva 

 fixes itself by the opposite end. 



Glaus ('92) has found that the scyphistomas of Cotylorhiza not only produce buds, 

 but that they produce them in large numbers. Scyphistomas reared from eggs that had 

 been laid in September, 1890, were kept alive in the aquaria at Trieste and Vienna 

 throughout the following winter and spring. No change was observed after the larvae 

 had reached the sixteen-tentacle stage, until the following July, when budding occurred. 

 The process was not restricted to a few well-nourished individuals, but seemed to be a gen- 

 eral and repeated phenomenon, and it resulted in a large increase in the number of larvae. 

 Clans' s brief description of the formation and fate of the bud, accompanied by three 

 figures, corresponds perfectly with what I have to describe in the following pages. The 

 strobilization, he says, took place in August, and was monodiscous. 



Another case of rapid multiplication of scyphistomas by budding is described by 

 Lacaze-Duthiers ('93) . A colony of these larvae, of unknown origin, was discovered in 



