ACTINIARIA 



2,5 3 f*> partly 19 38x3,55 p. Spirocysts in the tentacles very numerous 13 x 1,5 p to 29 x 3 ft. Lon- 

 gitudinal muscles of the tentacles and radial muscles of the oral disc rather well developed. Pairs of mesen- 

 teries 6 + 6 + 12; in addition to these pairs a fourth cycle in large specimens. Only the 6 first pairs with 

 pennons, which are strong, furnished with high folds and rather richly ramificated, especially in the inner 

 and outer parts. Parietal muscles weak, with somewhat low and sparse folds, expanded over all the outer 

 lamellar part of the mesenteries, not sharply outlined from the other longitudinal muscles, not expanded 

 upon the column. Muscles of the mesenteries of the second and third cycles recalling the parietal muscles 

 of the first cycle, but with more numerous folds. Marginal stomata present. Filaments only on the mesen- 

 teries of the first order and on the distal part of the mesenteries of the second one. Ciliated streaks of usual 

 type. Rather numerous acontia with large nematocysts. Reproductive organs on the first pairs and on the 

 distal part of the second pairs. 

 Colour? 



Dimensions: Largest specimen from Greenland in contracted state: Length 1,6 cm, breadth 

 about 0,9 cm. Another specimen was 1,1 cm long and i cm broad, the inner ten- 

 tacles 0,3, the outer 0,2 cm. Specimen from Siberia: Length 2 cm, breadth i cm. 

 Occurrence: Greenland without distinct locality, 3 sp., West-Greenland Nordre Stromfiord 375 

 380 m. (Nordmann, St. 2). 

 Bear Island (1886), i sp. 

 Spitzbergen. King Charles land 785o' N. 293g' E. 60 70 m. Clay (Sw. Spitzbergen- 



Exp. 1898), i sp. 

 Arctic Ocean of Siberia. 2 miles north of the winter station of the Vega (Vega- 



Exped.), i sp. 



Exterior aspect: The column is much more high than it is broad and, according to the state of 

 contraction, now more broad in the distal part, now in the middle. The proximal end is now flattened, now 

 physa-shaped, expanded or involved. In consequence of the strong longitudinal contraction of the body 

 the column shows numerous circular furrows. The column is smooth, without cuticle, papillae and acrorhagi, 

 but with a broad fossa. The distal margin is distinct. The insertions of the mesenteries are clearly visible 

 where the ectoderm is lost ; probably there are longitudinal furrows, corresponding to the insertions of the 

 mesenteries. The tentacles are most likely hexamerously arranged, in four or five cycles. The maximal num- 

 ber is about 96, in the reproduced large specimen (PI. i, fig. 31) I namely counted between 80 und 90 ten- 

 tacles. Probably some tentacles may have been torn off as the preservation of the tentacles was very bad. 

 The tentacles are conical, short, not longitudinally sulcated, and not swollen in the apex, the inner tentacles 

 are about one third longer than the outer ones. The oral disc is probably not wide, it was not well preserved. 

 The actinopharynx is of ordinary length and folded. The two siphonoglyphes are not very distinct and their 

 aboral prolongations short. 



Anatomical description: The ectoderm of the column, of the tentacles and of the actinopharynx 

 is high and much thicker than the mesogloea. No cuticle is found. In the different regions of four specimens 

 the nematocysts and the spirocysts show the following size. 



The Ingolf-Expcdition. V. 9. 



