C2 MEDUSA. I. 



tlie same size, whereas in octocostahtm the maturity is accomplished, and the growth comes to a stand- 

 still, when the individual is only about 12 mm high, and while half the number of the tentacles have 

 not yet reached full size. 



The question, whether campanula and octocostatniii are varieties or independent species can 

 only be solved by direct comparison of specimens of both forms. Particularly it must be examined, 

 whether campamila possesses the same peculiar subumbrellular lines of nematocysts, which in octoco- 

 stahtm issue from the circular vessel running towards the base of the manubrium. Mayer expressly 

 states that such lines are not yet found in campanula. Until these lines have been found, the Ameri- 

 can species must be regarded as specifically different from the European species. 



Mellcertum octocostatum (M. Sars). 



Plate I, fig. 10; Plate III, fig. S. 

 Oceania octocostata M. Sars 1835. Beskrivelser og lagttagelser ... — P- 24. PL 4, P^ig. 9. 

 Melicertum campai/nldf/tm Ehrenberg 1836. Akalephen des rothen Meeres ... — P- 77- Taf. VIII, 



Fig. 5—7- 

 Aequorca octocostata Lesson 1843. Histoire naturelle des Zoophytes. — p. 312. 

 Stomobrachiiim octocostatum Forbes 1848. British Naked-eyed Medusae. — p. 30. PI. IV, fig. i. 

 Aleticertiim pusillum Agassiz 1862. Contrib. Nat. Hist. U. S. A. Vol. IV. — p. 349. 



— — KoUiker 1864. Wiirtzburger naturwiss. Zeitschr. Bd. 5. — p. 233. 

 Melicertidium octocostatum Haeckel 1879. System der Medusen. — p. 138. 

 Melicertum — Mcintosh 1890. Ann. Mag. Nat. Hist. Ser. 6. Vol. V. — p. 304. 



— campanula Linko 1904 b. Zool. Studien im Barents-Meere. — Zool. Anzeiger. Bd. XXVIII. 



— p. 218. 

 Melicertidium octocostatum Browne 1905 a. Medusae . . . Firth of Chde. — Proc. R. Soc. Ediub. Vol. 



XXV, Part IX. — p. 762. 



Melicertum octocostatum is one of the most pretty and elegant among the medusse of the 

 northern seas. It seems to be fairly common; the number of specimens in the possession of the 

 Zoological Museum is not large, it is true, and the records in the literature are likewise, as a rule, 

 dealing with a comparatively small number of specimens. Only Mcintosh states that he has foimd 

 the species in considerable quantities at St. Andrews. But the journals of the "Thor" frequently men- 

 tion a "yellow-rayed medusa", which undoubtedly means this species, as being found in considerable 

 numbers, among others at the coasts of Iceland. In the following record of the distribution of the 

 species I have not, however, thoiight it advisable to pay regard to these records of the journals, but 

 I restrict myself exclusively to mentioning the preserved material in ni)- possession and the statements 

 of the literature. 



Description: The umbrella is bell-shaped. The gelatinous substance is fairly much thickened 

 in the apical part of the bell, while the side-walls are thin-walled. The largest diameter is a little 

 above the margin of the bell. 



The stomach is, when contracted, longitudinally folded in 8 folds, and there are apparently 8 

 short, recurved mouth-lips. Sars (1835), however, states that "When these 8 folds are extended, which 



