﻿Jan., 1856.] elliott society. 81 



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though alternately long and short, still are identical with each other 

 in structure, and setting aside the single circumstance that they 

 are yet unprovided with ocelli, as before remarked, differ in no 

 essential respect from those of the parent. When we consider the 

 transformation of the lobed margin of the young Sarsia bud into 

 the unbroken border of the adult, there is no difficulty in supposing 

 an analogous metamorphosis of that part in the present instance. 

 But there still remains one notable difference between this last of 

 the observed stages of the Larva and the structure of the adult 

 Turritopsis, and this consists in the circumstance that Turritopsis 

 has but four radiating tubes, while there are no less than twice 

 that number of triangular prolongations of the digestive cavity in 

 the larval medusa. 



But if this Larva be not metamorphosed into Turritopsis, the 

 only other supposition which appears to me to present any proba- 

 bility, is that of gemmation. It is not impossible that the present 

 larva may live for some time, and at a later period, develop Turri- 

 topsis-buds. If it should so prove, however, this would evidently 

 be not strictly analogous with the development of the Sarsia from 

 its larva Coryne. But with the development of Sarsia-buds 

 from the free swimming Sarsia, — it would be the budding of one, 

 and that a perfect form of Medusa, from another and an imperfect 

 form of Medusa, not the budding of a perfect Medusa from an 

 Hydroid. It would also be, in some respects, analogous to the de- 

 velopment of a Hooded-eyed Medusa, from its Scyphystoma-Strobila 

 that singular combination of metamorphosis and fissiparous multi- 

 plication, — analogous in the circumstance that a perfect is devel- 

 oped from an imperfect Medusa, but diverging in the circumstance 

 that, in this instance, the pullulating takes the place of the fissi- 

 parous method of multiplication. 



It will be well, nevertheless, in seeking for the remaining history of 

 this Medusa, to bear in mind the remarkable fissiparous multiplica- 

 tion of individuals observed by Kolliker, in Stomobrachium mirabile, 

 while gradually developing itself into Mesonema coerulescens — 

 fission, in this instance, taking place after the Medusa form had 

 been unmistakeably assumed, and even after sexual organs had 

 appeared. (Zeitsch. f. Wissensch. Zool. iv. Bd. p. 327.) 



It now remains to say a few words with regard to the histological 

 structure of this embryonic form of Medusa. Its whole structure 

 at this time appears to be eminently cellular, nothing which can 

 be certainly considered a fibre being discoverable. In contraction, 

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