CTENOPHORA. 



may be regarded as fairly certain that the genus Lesueuria cannot be maintained. It represents only 

 mutilated specimens of Bolina (and perhaps also other Lobatse), which have lost their lobes. Still less, of 

 course, can the family Lesueuridee, established by Chun, be maintained. As a character of this family 

 Chun regards the slight development of the lobe vessels, necessarily following from the rudimentary 

 condition of the lobes. It may not be superfluous to point out that the otherwise excellent fig. i, PL 3, 

 of Milne Edwards does not show the course of the vessels in the lobes. The small vessels pro- 

 ceeding from the base of the auricle a little way along an "appendice tentaculaire" and ending blindly 

 a short way from the auricle, I would suggest to represent the beginning of the marginal vessel of 

 the lobe. The upwards directed continuation of the subventral vessel may be said with certainty not 

 to be in connection with the other vessels at the base of the auricles, as stated by Milne Edwards; 

 it is the vessel which forms the windings within the lobe; I have found the development of the 

 vessels within the regenerating lobes of Bolina to begin in exactly the same way with the formation 

 of the upward directed branch of the subventral vessels. -- For L.hyboptera Agassiz certainly gives 

 a figure (28) showing "the connection between the lateral and longitudinal ambulacra, forming a cir- 

 cular tube round the actinostome"; but the figure is a mere sketch, which can decidedly not be re- 

 garded as a valid proof of such a condition of the lobe vessels really existing here, contrary to what 

 obtains in all other Lobatse, -- the more so as Agassiz himself states (Op. cit. p. 25) that "it differs 

 in no essential way in its mode of formation from what we observe in Bolina". 



The definite proof of the view of the Lesueuria here set forth must be given along the exper- 

 imental way; if it is right, as I cannot doubt, the "Lesueuriae" will, if kept under favourable con- 

 ditions, regenerate their lobes. Meanwhile, till the contrary has been prooved, the Lesueuria must 

 be regarded only as a mutilated Bolina or other Lobate. -- It is also worth recalling that Agassiz 

 states the L. hyboptera to be abundant in September, viz. the time when the Beroe is recorded to be 

 broken to pieces by heavy storms. 



Cestus Veneris Lesueur. This species, which is otherwise not known to occur North of 

 40 5olatN. in the Atlantic, is recorded by N. Wagner 1 ) to have been found in the White Sea (Solo- 

 wetski Bay), in the middle of the summer, and even rather commonly. Chun (Ctenophoren d. Plank- 

 ton-Exp. p. 20), Vanhoffen (Ctenophoren, Nordisches Plankton, p. 6), Romer (Ctenophoren, Fauna 

 Arctica, p. 86) and Moser (Japanische Ctenophoren, p. 12, 14) suggest that it is probably another, un- 

 described, arctic species of Cestus which Wagner has observed here. I would not be inclined to 

 adopt this suggestion. That the influence of the Gulf Stream is felt as far northwards as both the 

 White Sea and Spitzbergen, is certain, and then it would not seem impossible that the Cestus might 

 be carried northwards under certain especially favorable conditions - - in spite of Romer's definite 

 assertion that "an einem Transport durch die Auslaufer des Golfstromes auf so weite Entfernungen 

 kann bei einer so zarten und typischen Warmwasserform nicht gedacht werden". That an otherwise 

 unknown arctic species of this genus should exist, does not appear very probable, as it could then 

 scarcely have avoided being detected by some of the numerous observers of arctic Ctenophores; on 

 the other hand, it seems hardly possible that Wagner could have mistaken any other animal for a 

 Cestus. The correctness of Wagner's observation can then scarcely be doubted. 



') N. Wagner. Die Wirbellosen des Weissen Meeres. I. 1885. p. 54. 



