48 



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 Ok;en(i8i5) MelicertianK 

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

 (1829, p. 105 — 107 has 4 species of Gen. MeUcertum Oken, all of which have 4 radial canals: M. campa- 

 nula Fabricius, M. campanulatum Chamisso, M. pem'cillaluin, and M. pusillunt Swartz. — Melicertiun 

 campamda 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 (Morch 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 (40—60) tentacles, found at the coast of Norway. The next )-ear 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 Meh'certum campanulatuvi Eschscholtz, which, as mentioned 

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

 Thompson (1843, P- 281) as MeUcertum catnpamtlatum Ehrenberg. — Sars's medusa was included 

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

 p. 30, Plate IV, fig. I) as Stomobrachium octocostahim. 



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 MeU- 

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

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

 of a family Melicertidcc^ which is characterised by the possession of 8 radial canals. Agassiz referred 

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

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

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

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

 thorough and clear description of MeUcertum catnpanula sensu L. Agassiz, but A. Agassiz, like his 

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

 rightly remarks : '■'■Melicertutn has reall}' become a new genus, and with a new t\pe 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 MeUcertum campanula, and when that name is used for medusse 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- 



* In the front-list of contents in Ok en's Lehrbuch der Zoologie, erste Abth., MeUcertum 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 Melici-rtum 

 is 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 verliingerte Magen, lost sich in viele Hare auf — Mdicerta''. 

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



