CTENOPHORA. 79 



Gefasses angedeutet waren, auf der Oberflache der Lappen anderer Arten anslaufen" (Op. cit p. 182). 

 It may then not be superfluous to say, that I have found no particular difficulty in observing these 

 windings, and that I have found them in general corresponding with the representation given thereof 

 by L. Agassiz (Op. cit.), especially in his Fig. 4, PI. 7 and fig. 7, PI. 8. The median fold is always 

 simple, while the two lateral folds have generally two smaller, secondary folds, whichj may again be 

 subdivided. That the windings will prove to be more complicated in such large specimens as those 

 observed by Vogt & Yung, is very probable. It is worth remarking that the windings in the two 

 lobes may be somewhat different, as was also observed by Vanhoffen (Gronlandische Ctenoph. p. 19). 



The description of the muscular system given by Vogt & Yung is not very satisfactory; 

 though I have not studied the arrangement of the muscles in all details, I can give some additional 

 information thereof. The "mighty" retractor muscles of the apical organ, also described by Chun 

 (Monogr. p. 292; Dissogonie, p. 82, fig. i), who states them to go from the apical organ to the basis of 

 the lobes -- I have certainly observed; but I cannot agree that they are so very strong, and I have 

 found the fibres to be attached to the subventral vessels, not reaching to the lobes. Inside the pec- 

 uliar netshaped musculature on the adoral side of the lobes are found some longitudinal muscles, con- 

 verging towards the mouth. These, of course, serve to open the lobes, being the antagonists of the 

 netshaped muscles. From the meridional vessels radial muscles run inwards; on the contraction of 

 these muscles the costse are retracted, the skin folding over them. Other muscular threads serve to 

 draw aside the folds of the skin so as to expose again the costse. But I shall not enter here on the 

 details of this delicate muscular system. It may be observed that even when the costse are fully 

 exposed there is seen a distinct line along each side of them, the margin of the folds which cover 

 them when retracted; the costse thus lie in concave ridges. Also the intercostal areas are slightly 

 concave on the sides of the animal, while at the apical pole they are distinctly convex. 



The wonderful researches of Chun on the dissogony having been made on the Mediterranean 

 Bolina, which would appear to be only a local form of B. infundibulum, the question naturally arises, 

 whether dissogony occurs also in the form from the North European coasts; this question becomes 

 the more interesting, as Chun has found that the dissogony "nur unter dem Einfluss einer erhohten 

 Oberflachentemperatur des Seewassers eintritt" (Dissogonie, p. 103). Though I have not had occasion 

 to study myself the newly hatched young of Bolina, I think it can be said with rather great certainty 

 that dissogony obtains also in the specimens of our seas. As stated above (p. 70) it can scarcely be 

 doubted that the young Ctenophore from Helgoland, thought by Gar be (Op. cit.) to be the young of 

 Pleurobrachia rhodopis, is really a young Bolina. In Taf. XXXVII, fig. 18 he figures a section of a 

 specimen 0-5"' in diameter, in which the genital organs are already in full activity, producing eggs 

 and spermatozoa. As in the specimens studied by Chun only 4 genital organs are developed. They 

 lie close to the tentacle bases, so that there would appear to be a difference here between this specimen 

 and those studied by Chun, the latter having the genital organs developed along the subventral 

 vessels, not along the subtentacular. This difference, however, is only apparent. In the figure quoted 

 of Garbe the testes are represented as lying close to the tentacle, the ovaries on the other side. 

 This is a proof that the vessels in which the genital organs have developed are really the subventral; 

 if it were the subtentacular the arrangement of the ovary and testis would have been the reverse. 



