MEDUSA. I. ,j 



as occurring at the coast of Greenland', it is due to Liitken who, not being aware of the mistake 

 of Agassiz, inchided the species in his list of the medusae of Greenland, whence it proceeded 

 to the lists of Winther and Fewkes. This is rather annoying, it is true, and may, possibly, still in- 

 volve misunderstandings; but I am not able to comprehend, how this danger might in any way be 

 removed by the introduction of the name Mcliccrtidiniii in the place of Meliccrtuui. 



Altogether, it seems to me that the use of the generic name Mclicertnm involves no 

 danger any more for a continuation of the confusion. Since 1843 the names Melicerta and Mclicertnm 

 sensu Peron & Lesueur, Oken, Eschscholtz have been applied to no other species than cainpaniila. 

 '•^Medusa cainpaiiiiia' Fabrichis has to be excluded from the system, as it has not been identified with 

 certainty, and all records of "-Mel/ccrf/nj/ cainpaniihi" from Greenland have to be omitted. When this 

 is remembered, nobody can have an>- doubt as to the meaning of the names Melicrrtuiii canipautila 

 Agassiz, Alelicertniii gcorgicitiii Agassiz, and Meltcerfiiiii octocostatniii (Sars). 



When, thus, Melicerfiiiii. Agassiz cannot involve misunderstanding this generic name seems to 

 me to be preferable to Mcliccrfidiitiii^ because Mclicertttiit is older and is correctly defined, whereas 

 the definition of Mcliccrtidiniii is incorrect. 



The species of the genus Mclicertnm. 



Alelicertuni praboscifcr Alaas (1897, p. 19) is uudonbtedl\- a Trach\niedusa. — Mayer (1910, 

 p. 209) includes Meliccrtclla paiiocto Haeckel among the species of Mcliccrtniii, though he indicates 

 the possibility that it may belong to the genus Mclicciissa. In any case, tiie presence of ocelli on 

 the base of the tentacles excludes the species from the genus Mclicertnm. 



Meliccrfniu georgicniii A. Agassiz (L. Agassiz 1862, p. 349; A. Agassiz 1865, p. 135) seems to 

 differ but very slightl}' from Mcliccrtnni campannla Agassiz; but since the species was described, no 

 medusa belonging to the genus Meliccrtnm has been found in the I^acific; it is impossible, therefore, 

 to state, whether it is identical with the Atlantic-American species. Mcliccrtnni georgicnm is found in 

 the Gulf of Georgia on the west coast of U. S. A. 



The two Atlantic species, the European Meliccrtnm octocostatniii Sars and tlie American M. 

 campannla Agassiz, are undoubtedly nearh' related. In the first-mentioned species the height of the 

 bell is about 12 mm, the diameter about as much or a little .smaller, and there are fairly constantly 

 64 longer and 64 shorter tentacles. In Mcliccrtnin campannla the height and the diameter amount to 

 about 25 mm, and in the full-grown individual the tentacles arc all alike; Agassiz and (after him) 

 Mayer state their number to be about 70. There does not seem to be any important difference with 

 regard to the shape of the bell, the manubrium, or the gonads. In campannla^ it is true, the gonads 

 are said to reach entirely to the circular vessel, whereas in octocosfatnin a small distal part of each of 

 the radial canals is free of gonads; but this feature may, as in other medusae, be subject to much 

 variation. The tentacles of octocostatnm are going to be further mentioned below; here I shall onl\ 

 remark that there is no decisive difference between the two series of tentacles. Mcliccrtnni campanula 

 might very well be considered as a variet)- which attains a more exuberant development, 1. e. when 

 the individual is mature it has a comparatively large size, and all of the tentacles are developed to 



" My record of Mfliceitton campamila as occurring at Frederikshaab in Greenland (I9'.>' P- ^''^ ^"^' '9'-i.' P- 424) 's 

 due to a mistake which I verv much regret. 



7* 



