86 CTENOPHORA. 



place. Further I must state, concerning the arrangement of the costse, that it may be found quite 

 alike in B. cucumis; thus e.g. a large specimen from Naples shows exactly the same arrange- 

 ment as that seen in fig. 17 of Moser. The characters pointed out by Moser as distinguishing 

 B.Clarkii from cucumis thus appear to me of rather slight value. Some more weight I would ascribe 

 to the different coloration ; L,. A g a s s i z (Op. cit. p. 288) states "from notes made years ago . . . that the 

 rows of locomotive flappers have on each side a band of yellow and brown stellate dots, and that the 

 edge of the mouth, as well as the fringes around the circumscribed area, were dotted in the same 

 manner". This coloration differs rather much from that of B. cucumis, so that it seems quite probable 

 that B. Clarkii is really different from B. cucumis. But the descriptions hitherto given are by no means 

 sufficient. Renewed careful observations on living material are needed for deciding the question about 

 the specific value of both B. Clarkii and cyathina ( which .may perhaps prove to be identical ), as 

 well as of the other Ctenophores of the North American Coasts 1 ). 



While it is quite probable that there will prove really to exist two different species of Bcroe 

 at the North American Atlantic Coasts, it may be said with rather great certainty that only one species 

 normally occurs in the North European Seas. It is true that Hartlaub 2 ) mentions a small Bcroe from 

 Helgoland, which he regards as specifically distinct from B. cucumis, without giving, however, the char- 

 acters by which it should be distinguished. Though I have been unable to obtain specimens of this 

 form for study, as it has not been observed more recently there, I cannot regard it as doubtful that 

 it is really only B.cucumisi>\ -- Another thing is, that perhaps Beroe Forskalii may sometimes occur 

 in the North European Seas (Comp. below, p. 92); but there can, of course, be no question of Hart- 

 laubs' small Beroid being this species, the more so as it was found nearly the whole year round, 

 which could not have been the case with B. Forsk&lii. 



Having the opportunity last summer (1911) of studying a fair number of living specimens of 

 Bcroe cucumis at the Biological Station of Trondhjem I paid attention to the possible existence of 

 other characters by which to distinguish B. cucumis from B, ovata, instead of the character of the 

 pharyngeal vessels, which I had then already found to be without the value of a certain distinguish- 

 ing character. I thought especially that some difference might possibly exist in the distribution of 

 the peculiar sabre-shaped cilia of the mouth-edge. In Beroe Forskalii they are shown by Chun (Mono- 

 graph, p. 185, Taf. XIV, a. fig. 8) to radiate inwards in attenuating bands from a continuous band at the 

 mouth-edge; Chun does not describe their arrangement in B. ovata, but on the specimens at my dis- 

 posal I found them to be arranged only in a simple band along the edge. The same was found to 



') The Berof ovata mentioned by I. W. Fewkes (Notes on Acalephs from the Tortugas, with a Description of New 

 Genera and Species. Bull. Mus. Comp. Zool. IX. 1882. p. 251) is probably the same as B. Clarkii. Whether this is also the 

 case with the Beroe ovata mentioned by Ch. W. Hargitt (The Medusae of the Woods Hole Region. Bull. Bureau of Fisheries. 

 XXIV. 1904, p. 73) as being found commonly at Woods Hole (in 1901), seems very doubtful. Judging from the few notes 

 which are found under the two species "ovata" and "cucumis" it appears rather evident that both are really B. cucumis ; it is 

 only the large specimens ("4070 mm in polar diameter") which are distinguished as B. ovata, while the smaller specimens 

 ("15 -20 mm in polar diameter") are designated as B. cucumis. 



2 ) Cl. Hartlaub. Beitrage zur Meeresfauna von Helgoland. IV. Die Coelenteraten Helgolands. Wiss. Meeresunter- 

 suchungen. Abth. Helgoland. N. F. II. 1894. p. 204. 



3) Also Romer (Op. cit. p. 83) is inclined to regard it as identical with B. cucumis, suggesting "dass sie in dem war- 

 meren Wasser der Nordsee nicht die Grosse erreicht, wie die Exemplare der kalteren Stromungen, sondern hier schon bei der 

 geringen HShe von i cm geschlechtsreif wird". This suggestion, of course, must be dropped on the demonstration of the 

 B. ovata of the Mediterranean and the warm Atlantic regions being identical with the B. cucnmis of the North Atlantic. A quest- 

 ion to be yet examined is, however, at what size B. cucumis becomes sexually mature in the different regions in which it occurs. 



