26 OCEANIA. 



Genus IV. Oceania (nom, Peron), (1809), 



Tiara and Oceania (pars). Lesson. 



Umbrella conical, mitrate, or rarely globular; ovaries four, double, convoluted, 

 lining the cavity of the peduncle ; vessels simple, four ; margin of the umbrella with 

 few, or many, similar tentacula ; no conspicuous muscular bands ; mouth of the 

 peduncle four-lipped. 



The natural wish to preserve a name in a manner consecrated by long usage, has induced 

 me to retain that of Oceania, even at the risk of employing it in a somewhat different generic 

 signification from any of the many meanings hitherto given to it, and thereby perhaps almost 

 increasing confusion. In such a case it becomes a toss-up whether the conservative or the 

 destructive process be best ; but as evien the most virulent of reformers gladly seize on an 

 excuse for upsetting usurpers, whilst good-natured people are inclined to stand by ancient 

 dynasties, however bad, rather than risk the chances of change, I think it safest (though 

 prepared to do either) to adopt Oceania as a genus for the present, and, by defining it more 

 strictly, endeavour to make it more useful. 



The term Oceania has been so often and generally applied to the Medusa pileata of 

 Forskal, and similar forms, that I think it best to restrict it to that group. Peron, who first 

 founded the genus, included them within it, though it is doubtful whether he would have 

 regarded the Forskalian species as the type. Lesson gives the generic name of Tiara to 

 AI. pileata ; and those who are extremely anxious to use a new name may adopt it. Eschscholtz 

 included its allies in his view of the genus, but also some very distinct forms. 



Using it in the sense here taken, the genus consists of those mostly mitre-shaped 

 Medusae, which have an ample dependent peduncle and convoluted ovaries within, a conspicuous 

 character indicating a close relationship with Turris. Their muscular tissue, however, is not 

 nearly so highly organized as in the last-named genus, whilst the uniform character of the 

 tentacles separates them from SapJienia. 



The species of Oceania range throughout the European seas, extending into the 

 Mediterranean. They will probably be found much more numerous than at present recorded. 

 Sars has described and figured in his ' Beskrivelser,' &c., 1835, a species with twenty-four 

 tentacula, and resembling in form our O. episcopalis, which may probably inhabit our seas. 

 He names it O. ampullacea, and describes it as ovato-campanulate, terminating above in an 

 oblong, conical appendage ; the mouth furnished with very short fimbriations ; the length of 

 the body about an inch. Forskal's name of "Medusa pileata" has been applied to more than 

 one species of the genus. He described it as " ovato-campanulate, terminated above by a 

 hyaline sphere ; within containing an oblong, red nucleus ; the margin fringed with numerous 

 tentacula, having yellow bases." His figure does not show clearly the number of tentacula, 

 but they appear to have been sixteen and upwards. The animal figured by Ehrenberg as 

 Medusa pileata from the Norwegian seas, has a yellow nucleus, and appears to be the 

 Oceania ampullacea. The colour of the nucleus, the general form of the umbrella, and the 

 number of the tentacula, are evidently the most important sources of character in this genus, 

 and should be carefully noted. 



