ATLANT. DEEP-SEA EXPED. 1910. VOL. III.] 



CTENOPHORA. 



as is the case in Beroe, where there is otherwise a similar 

 arrangement of proliferations from the meridional vessels. 



The pharyngeal vessels issue close to the tentacular 

 basis. They proliferate like the pharyngeal part of the 

 subsagittal adradial vessels; in the lower part the proli- 

 ferations are longer, nearly meeting in the sagittal middle 

 line of the pharyngeal wall, but they do not form ana- 

 stomoses. At the oral edge the pharyngeal and meridi- 

 onal vessels end blindy. (PI. I, fig. 6). 



The pharynx is very large. In the upper half its 

 lumen is nearly obliterated on account of very strongly 

 developed, sagittal folds, which do not correspond to 

 the usual pharyngeal folds of Ctenophores. t They 

 are arranged in four longitudinal bands, following the 

 four subsagittal adradial vessels, from which proliferations 

 pass in among the folds. The true pharyngeal folds 

 follow the pharyngeal vessels, from which likewise proli- 

 ferations pass into them ; they are much less developed, 

 but are double as usual. (Textfig. 2). The lower half 

 of the pharynx is more spacious. (PI. I, figs. 5 — 6). The 

 whole of the pharynx is compressed in the sagittal plane, 

 as typical in Ctenophores, but this feature is obliterated 

 in the upper part on account of the strong development 

 of the sagittal folds, except at the uppermost end. Here 

 the walls are closely appressed, so as to get almost the 

 appearance of a narrow vessel, as seen from the outside 

 (textfig. 1). The walls are here strongly ciliated, this part 

 evidently corresponding to the ciliated pouch of the typical 

 Ctenophores. The oesophagus is not long, but distinct, 

 compressed in the sagittal plane as usual. On the inner 

 lips and the outbending wall (the outer wall of the dia- 

 phragm) there appears to be a powerful ciliation. 



The histological structure of the gastrovascular canals 

 I have not been able to see in a satisfactory way. In 

 the proliferations there are two lateral thickenings, the 

 outer an inner side being thin; in the meridional vessels 

 there appears to be only one thickening, on the outer 

 side, the whole inner side being thin-walled. Rosettes 

 could not be discerned. 



In the meridional vessels and even in the prolifera- 

 tions from these, far down in the body, I have found, in 

 the broken specimen, some large Copepods. This is, 

 however, scarcely a definite proof that this Ctenophore, 

 contrary to the custom of all the rest of them, digests its 

 food not in the pharynx, but in the gastrovascular system. 

 It may perhaps be due to the Copepods having them- 

 selves penetrated into the cavities of the digestive system 

 during the capture in the hoof, after the specimen was 

 broken. They do not show signs of having been under 

 the digestive action of the Ctenophore. The strong deve- 

 lopment of folds in the pharynx would also seem to 



afford evidence for the absorption of the food in the 

 pharynx after the usual Ctenophoran fashion. 



The arrangement of the gonads could, unfortunately 

 not be made out. Probably they will be found to have 

 their place in the proliferations of the meridional vessels, 

 in the same way as in Beroe; but even in sections I 

 could see nothing which could be definitely recognized 

 as gonads. 



The tentacular apparatus (PI. I, figs. 5, 7, 9). 

 The tentacular basis is rather short slightly widened 

 at the lover end. It is not longitudinally divided, but 

 appears in sections to be built as usual, the tentacular 

 vessels with their ectodermal covering of colloblast-forming 

 cells occupying the sides, the root of the tentacle occu- 

 pying the middle part of the basis. It affords the unique 

 feature that the colloblast-layer sends a prolongation into 

 each of the subtransverse adradial vessels, continuing 

 nearly to the point, where it opens into the meridional 

 vessel. This is probably simply a fold of the colloblast- 

 layer of the tentacular basis, but I have been unable to 

 find out, how this peculiar arrangement — an ectodermal 

 prolongation lying within an entodermal tube — has arisen. 

 These two processes from the tentacular basis, very con- 

 spicuous on account of their yellow colour, give the 

 puzzling impression, that there are two lateral tentacles 

 to each tentacular basis: indeed, I thought so myself at 

 first, before I had yet studied the anatomy of the animal 

 more closely. 



The tentacle is, so far as I have been able to as- 

 certain, unbranched, but ends in a peculiar large knob. 

 (PI. I. fig. 9). This reminds one somewhat of the pecu- 

 liar appendages on the tentacles of Hormiphora ; but it 

 is certain that the knob here occupies the end of the 

 tentacle, and I have found only one such knob on each 

 tentacle. Its shape is somewhat different, now with a 

 constriction at the point, now without such constriction; 

 this is doubtles due to muscular contraction. It appears 

 to be completely covered with colloblasts, though these 

 have been lost in places in the preserved specimens. 



The tentacular sheath is directed downwards (PI. 

 I, figs. 5, 6) and opens at the oral edge, where the lateral 

 furrow ends. 



The colloblasts (PI. I, figs. 10 — 11) are compara- 

 tively large and beautiful objects. The spiral filament is 

 very strongly developed, but there is no central filament 

 to be seen. The grains of the cupule show a definite 

 arrangement in small rosettes. 



The jelly is very tough and resistent, nearly as car- 

 tilage. It is full of muscles, arranged rather regularly. 

 In tranverse sections the muscles are seen to go from one 

 rib to the other, while others go between the outer and 



