CTENOPHORA. 



Morch 1 ), Levinsen 2 ), RomerJ) and Vanhoffen4). These statements all rest on Fabricius' 

 old description, and it is a mistake when Vanhoffen (Op. cit. p. 16) thinks its occurrence at Green- 

 land "durch die Arbeiten von L, ii t k e n mid Levinsen geniigend beglaubigt". There are no specimens 

 of PL pileus from Greenland in the collection of the Copenhagen-Museum and as PL pileus is not 

 so very difficult to preserve in a tolerable conditition, this means something. Further Vanhoffen 

 did not observe the species at Greenland during his stay there, and neither was it observed by the 

 Danish expeditions to East Greenland or by the "Tjalfe" Expedition. It may be concluded from this that 

 Pleurobrachia pileus does not occur at the Coasts of Greenland. Having reached this conclusion 

 I was very pleased in finding later, in the work quoted of Dam as & Koefoed (p. 414), that they 

 did not observe the species at Greenland either, stating that PL pileus "n'existait certainement pas 

 dans la partie occidentale de 1'itineraire" (viz. at the East Coast of Greenland). 



From this then it follows that the Beroe pileus of Fabricius (Fauna gronlandica, p. 361) is not 

 the species now generally designated as Pleurobrachia pileus Fabr. The diagnosis given by Fabri- 

 cius: "Beroe globosa, costis octo, cirrisque duobus ciliatis" (which is a quotation from O. Fr. M tiller 

 (Op. cit.)) cannot give any clue to what species it really is, and neither do the accompanying remarks: 

 "hanc ssepissime vidi tempore autumnali in sinubus natantem, eleganter in acqua coloribus suis ni ten tern; 

 nunquam tamen ob debilitatem eius sufficienter contemplari contigit" give the clue. That it might 

 possibly be the same as his Beroe omtm, as is siiggested by Romer (Op. cit. p. 77), I would not think 

 very probable, judging from Fabricius' excellent observations on the latter species. The solution 

 of this question perhaps is given by the fact that recently a new species of Ctenophore, Pleurobrachia 

 crinata Moser has been discovered at Greenland, collected by Vanhoffen. I would suggest that this 

 is perhaps the real Beroe pileus of Fabricius. The common North Atlantic species, however, may well 

 keep the name pileus O. F. Mull. (nee. Fabr.). Nobody can tell definitely which species is really meant with 

 Martens' "Mutzener Rotzfisch". But it is certain that it is either Mertensia ovum or Pleurobrachia 

 pileiis, which both occur at Spitzbergen. There being no doubt about which species has the claim 

 of the former name, the name pileus Mull., (non Fabr.) with good right belongs to the northern 

 Pleurobrachia, in accordance with the almost universal use, and in spite of the fact that Fabricius 

 most probably used it in another sense. (It may be remembered that the author of the name pileus 

 is not Fabricius, but O. Fr. Miiller to whose Prodromus Fabricius refers under his Beroe pileus). 

 I agree that it is probable that Martens' "Mutzener Rotzfisch", to which the name pileus was given 

 by O. Fr. Mtiller, is the species now called Mertensia ovum, but as it cannot be put beyond doubt, there is, 

 in my opinion, no reason to alter the species-name of our most common Ctenophore; and even if it 

 could be proved definitely that the "Mutzener Rotzfisch" is really Mertensia ovum I would think this 

 case one of those, where an exception from the priority rule should take place. 



') Naturhistoriske Bidrag til en Beskrivelse af Gronland af J. Reinhardt, J. C. Schiedte, O. A. L. M0rch, 

 C. F. Lutken, J. Lange, H. Rink. (Sserskilt Aftryk af Tillsegene til "Gronland, geografisk og statistisk beskrevet af 

 H. Rink). 1857. p. 97. 



2 ) G. M. R. Levinsen. Meduser, Ctenophorer og Hydroider fra Gronlands Vestkyst. Vid. Medd. Nat. Foren. Koben- 

 havn 1892. (p. 7, PI. rhododactyla Agass.). 



3) F. Romer. Ctenophoren. Fauna Arctica. III. 1903. p. 77. 



4) E. Vanhoffen. Die gronlandischen Ctenophoren. Bibl. Zool. VIII. 1895. p. 21. 



