20 DEVELOPMENT OF 



consequently that the genus Strobila, which was in fact 

 only an early stage in the development of a known 

 animal, and probably also the whole genus Epliyra (Esch.) 

 should be abolished. The observations themselves with 

 the illustrative figures, although dating from March 1837, 

 were first published in 'Erichson's Archiv,' (1841 — ersten 

 Heft.) In them the development of the young Medusa 

 after their liberation from the egg was described, and 

 their gradual transformation into the polypoid form of 

 the Strobila proved, from independent observations made 

 in September and October 1839. In which year, long 

 after his treatise had been already designed, Sars re- 

 ceived the ' Beiträge zur Naturgeschichte der Wirbel- 

 losen Thiere,' (Danzig, 1839) of Siebold, in which that 

 naturalist clearly proves the truth of the assertion made 

 by him in 1837, that the Medusa are generically divided, 

 and also describes the development of the ova of Cyancea 

 capillata, and the history of the infusoria-like fry pro- 

 ceeding from them, untu it assumes the form of attached 

 eight-armed polyps. 



Sir Graham Dalzell has at different times communi- 

 cated observations on the same subject (The Edinburgh 

 Philos. Jour., vol. xvii and xxi, extracted in Oken's Isis, 

 1838) ; but these observations are not only filled with 

 matters of which he has taken a false view, but also 

 contain phenomena which he has misunderstood, and 

 they have consequently been of no utility in science until 

 now that other fundamental researches have allowed of 

 their being correctly explained. 



What is particularly to be observed in the above de- 

 scription of the development of the Medusa aurita, and 

 what will scarcely have escaped the reader, is the remark- 

 able circumstance, that it is not the, at first, infusoria- 

 like creatures proceeding from the ova, which are trans- 

 formed into the perfect Medusa, but that each of them 

 passes into a polypiform creature {Scyphistoma- Strobila,) 

 the apparently detached portions of which after their 



