4 8 



MEDUSA. I. 



4 radial canals and a small number of tentacles, as it appears from the rather short and vague descrip- 

 tion. Peron and Lesueur (1809, p. 352) quoted the description of Fabricius and referred the 

 species to the genus Melicerta, established by these authors, and written by Oken (1815) Melicertum^. 

 Lamarck (1816, p. 508) called the species with the name of Dianaa campanula. Eschscholtz 

 (1829, p. 105107 has 4 species of Gen. Melicertum Oken, all of which have 4 radial canals: M. campa- 

 nula Fabricius, M. campanulatum Chamisso, M. penicillatum, and M. pusillum Swartz. Melicertum 

 campanula is mentioned again by Oken (1835, p. 226) with reference to the description of Fabricius. 

 - Lesson (1843, p. 313) called it Campanella Fabricii, and in M0rch's list of the Acalephs of Green- 

 land (M0rch 1857, p. 95) Fabricii medusa is included as Campanella campanula. 



In 1835 (p. 24) M. Sars described a medusa, Oceania octocostata, with 8 radial canals and 

 numerous (4060) tentacles, found at the coast of Norway. The next year the same species was figured 

 by Ehrenberg (1836, Taf. VIII, figs. 5 7), who does not seem to have known Sars's description. 

 Ehrenberg gives no description of the animal, but his figures are very good and leave no doubt as 

 to the identity of the species. It is peculiar, therefore, that Ehrenberg, in the explanation of the 

 plates, p. 77, refers this 8-rayed medusa to Melicertum campanulatum Eschscholtz, which, as mentioned 

 above, has 4 radial canals. Some specimens from the north coast of Ireland were identified by Wm. 

 Thompson (1843, P- 2 ^ 1 ) as Melicertttm campanulatum Ehrenberg. Sars's medusa was included 

 in the work of Lesson (1843, p. 312) as Aequorea octocostata, and in Forbes's Monograph (1848, 

 p. 30, Plate IV, fig. i) as Stomobrachium octocostatum. 



A medusa related to Oceania octocostata Sars was found in Massachusetts Bay, North America, 

 by L. Agassiz. It is quite unintelligible, that Agassiz should refer this medusa to the genus Meli- 

 certum Oken and identify it with Medusa campanula Fabricius. With Agassiz the genus Melicertum 

 gets an entirely new meaning and is even used (as appears from the note on p. 352) as the type 

 of a family Melicertida, which is characterised by the possession of 8 radial canals. Agassiz referred 

 four species to his genus Melicertum: i) M. campanula Fabricius; 2) M. pusillum Eschscholtz (which 

 is incorrectly identified with Oceania octocostata Sars, Melicertum campanulatum Ehrenberg, Stomo- 

 brachium octostatum Forbes etc.); 3) M. campanulatum Eschscholtz (non Ehrenberg); 4) M. georgicum 

 A. Agassiz, shortly described in a footnote on p. 349. - A. Agassiz (1865, p. 130 134) gives a 

 thorough and clear description of Melicertum campanula sensu L. Agassiz, but A. Agassiz, like his 

 father, regards the species as identical with Medusa campanula Fabricius. Browne (1905, p. 765) 

 rightly remarks : ''Melicertum has really become a new genus, and with a new type species, M. campa- 

 nula A. Agassiz (non Fabricius)". 



Since the forthcoming of the work of Agassiz the American species has always been called 

 by the name of Melicertum campanula, and when that name is used for medusae from the Atlantic 

 coast of North America, any doubt of the identity is excluded. But'the mistake of Agassiz has been 

 the cause, why the species for a long time to follow was recorded as occurring at the coast of Green- 



1 In the front-list of contents in Ok en's Lehrbuch der Zoologie. erste Abth., Melicertum is mentioned as the fourth 



genus of "Walmmanete", and reference is given to p. 125. Also in the alphabetic register in the rear of the book Melicertum 



i found with reference to p. 125. But if we look at p. 125, we will find that "Walmmanete" only includes three genera. 



Group D of Gen. Charybdea is characterised as follows: "Stiel verlangerte Magen, lost sich in viele Hare auf Melicerta". 



The name Melicertum is not found, nor the specific name campanula. 



