52 



MEDUSA. I. 



the same size, whereas in octocostatjim 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 canipamila and octocostalmii are varieties or independent species can 

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

 whether campanula possesses the same peculiar siibumbrellular lines of nematocysts, which in octoco- 

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

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

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



Melicertum octocostatum (M. Sars). 



Plate I, fig. 10; Plate III, f'g. 8. 



Oceania octocostuta M. Sars 1835. Beskrivelser og lagttagelser ... — p. 24. PI. 4, Fig. 9. 



Mclicertiini campaiinlatinii Ehrenberg 1836. Akalephen des rothen Meeres ... — P- 77- Taf. VIII, 



Fig- 5—7- 

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

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

 Melicertum piisillum Agassiz 1862. Contrib. Nat. Hist. U. S. A. Vol. IV. — p. 349. 



— — Kolliker 1864. Wiirtzburger uaturwiss. Zeitschr. Bd. 5. — p. 233. 

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

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



— campauitla Linko 1904 b. Zool. Studieu im Barents-Meere. — Zool. Anzeiger. Bd. XXVIII. 



— p. 218. 

 Melicertidium octocostatum Browne 1905 a. Medusae . . . Firth of Clvde. — Proc. R. Soc. Edinb. Vol. 



XXV, Part IX. — p. 762. 



Melicertum octocostatum is one of the most prett\' and elegant among the medusa of the 

 northern sea.s. 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 found 

 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, thought it advisable to pay regard to these records of the journals, but 

 I restrict myself exclusively to mentioning the preserved material in my possession and the statements 

 of the literature. 



Description: The mnbrella is belkshaped. 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 (1835I, however, states that "When these 8 folds are extended, which 



