go CTENOPHORA. 



deep-water form, which only now and then is carried to the surface under certain hydrographic con- 

 ditions, or that it is no separate form at all, but only a Bolina in a heteromorph condition, as suggested 

 by Va nh o f f e n (Gronlandische Cteuophoren, p. 18—19). (That the Lesueuria vitrea recorded from Scotland 

 by M'Intosh is really Bolina infundihiluvi, as pointed out by Vanhoffen (Gronland. Ctenoph. p. 19) 

 and Evans & Ash worth (Op. cit. p. 309) is another thing, not implying eo ipso that the true 

 Lesueuria is the same). Finally j\Ioser (Cteuophoren d. deutschen Siidpolar-Expedition, p. 178), thinking 

 that there is no support for the suggestion of Vanhoffen, expresses the view that the Lesueuria 

 "allerdings wahrscheinlich jetzt ganz ausgestorben ist", which would certainh- also account for its 

 not having been observed for more than 25 years. While there is no real support for the first 

 suggestion — and still less for the last one — , all evidence is for the assumption that the Lesueuria is 

 no separate form at all. On the other hand, I would not simply adopt the suggestion of Vanhoffen 

 that it is a heteromorph condition of Bolina, perhaps due to the dissogony'), and thus reall>- a 

 normal condition. In my opinion the Lesueuria vilrea is only a Bolina infundibiihini (or perhaps some 

 other Lobate) which has lost its lobes through mutilation, and the same I think will prove to 

 hold good of Lesueuria liyboptcra A. Agass. I have myself observed such mutilated specimens of 

 Bolina in/undibuluDi, which were exactly like Lesueuria and which I would have regarded as such 

 without the knowledge of the regenerative power of the Bolina. It is true that A. Agassiz (North 

 American Acalephce, p. 24) has noticed that mutilated specimens of Bolina are very like the Lesueu- 

 ria, and it should then be taken as an argument in favour of the distinctness of the Lesueuria that, in 

 spite of its likeness with the mutilated specimens of Boli)ni, it is maintained as a separate form, the 

 characters distinguishing it from the Bolina being the great length of the auricles and the position 

 of the mouth. But the length of the auricles (which I have found to be rather variable) may be as 

 great in Bolina, and the position of the mouth does not differ either in the two forms, if specimens 

 of the same size are compared. If in the specimen of Bolina copied from Vogt & Yung in the 

 fig. II of Vanhoffen's Cteuophoren (Nordi.sches Plankton) we imagine the lobes removed, the result 

 will be a Lesueuria not to be distinguished from tlie L. liyboptera of Agassiz, as copied in the 

 fig. 10 of the same work. Concerning the Lesueuria vilrea of Jililne Edwards there is only one thing 

 which makes me hesitate a little in regarding it likewise as belonging to Bolina infundibuluii/, viz. 

 the patches of j-ellowish and greenish colour shown on the costse in his figure i, PI. 2, the Bolina 

 being otherwise not thus coloured. This might perhaps indicate that the L. vilrea of Milne Edwards 

 really belongs to another Lobate; among the other Lobates known from the Mediterranean Deiopea 

 kaloklenola Chun would alone have to be taken into consideration here. But the narrow costse in 

 the quoted figure of Milne Edwards do not recall the broad costae of Deiopea, which, moreover, is 

 described as "voUkommen durchsichtig". 



Leaving the question undecided, to which species the Lesueuria vilrea should be referred, it 



■) "Die von Agassiz (an der Ostkuste Nordamerikas) beobachteten Arten Bolina alata, Mnemiopsis Gardeni, Mnemiopsis 

 Liidyi imd Lesueuria hyboptera scheinen sich nur von Bolina septenlrioiialis durch dass wechselnde Verhaltnis der einzelnen 

 Organe zu einander, der Randlappen mit den Kanalen zu den Aurikeln und dem mehr oder weniger tief herabhangendeii 

 Mundrohr zu unterscheiden, Verhaltnisse, die teils durch Kontraktionszustaude erzeugt sein konnen, teils auch vielleicht auf 

 verschiedene AlterssUifen oder durch heteromorphe Stadien derselben Art, bedingt durch die von Chun bei Cteuophoren 

 entdeckte Dissogouie, oder eudhch auf wirklicher Artverschiedenheit l)eruhen konnen". (Gronlandische Cteuophoren; p. 19). 



