ACTINIAKIA 



that the genus probably belongs to the Paractidae. Now my suggestion (1902 p. 43) that the genus is related 

 to the family Antheadae (Actiniidae) is correct — at the time of this statement I had only had the oppor- 

 tunity of examining the most distal i^art of the original specimen in wliich only fragments of the column 

 were left. In reality the genus is closely related to the family Gonactiniidae. It is true that it differs in several 

 respects from Protanthea and Gonactinia, above all as regards the structure of the tentacles and the pre- 

 sence of a greater number of perfect mesenteries, but in spite of these differences I think that it is not ne- 

 cessary, at least not at present, to establish a special family for Sidcractis, which estabhshment in such a 

 case would have to be founded for one thing on the structure of the tentacles and on the greater number 

 of perfect mesenteries. Thus I refer Sideractis to the family Gonactiniidae together with Protanthea and 

 Gonactinia. The genus contains only one known species, Sideractis glacialis Dan. 



Sideractis glacialis Dan. 



PI. I. Figs. 17 — 19. 

 Sideractis glacialis n. sp. Danielssen 1890 p. 14. PI. i. fig. i. P. 7. figs. 10, 12. 



Diagnosis: Pedal disc wide, indistinct, with undulated border. Column with longitudinal furrows 

 corresponding to the insertions of the mesenteries. Tentacles 24 — 38, in the stadium of 24 tentacles arranged 

 in three cycles (6 + 6 + 12). Arrangement of the tentacles in later stadia more irregular through the de- 

 \-elopment of new tentacles in the transversal plane (always?). Papilliform elevations composed of ecto- 

 dermal thickenings, containing numerous spirocysts. Stinging capsules of several kinds in the apex of the 

 tentacles, partly typical spirocysts, partly capsules with thread densely rolled-up (size: 86 — 106 X 12 — 14 //), 

 partly of equal width with the basal part of the spiral thread distinct and of two different sizes 55 — 79 X 

 5 (I and 24 — 29 X 3 /i. Stinging capsules in the actinopharynx with thread densely rolled-up, 53 — 60 X 

 13 — 17 n, and others of equal width as those in the apex of the tentacles, 24 — 31 (seldom 46) X 5 — 6 [i. 



Colour: Almost transparent. Column and tentacles greenly .sliimmering, the oral disc redly so. 

 Apex of the tentacles with a white anuulus. Actinopharynx and filaments pale red (Danielssen). 



Dimensions: In Hving state. Diameter of the pedal disc 2 cm. Height of the column 0,5 cm (Da- 

 nielssen). In preserved state: i) The type specimen: Diameter of the oral disc 1,5 cm. IvCngth of the inner 

 tentacles 0,6 cm breadth 0,25 cm, length of the outer tentacles 0,35 — 0,4 cm. 2) The best preser\'ed 

 specimen from Sunde: Length of the column 0,4 cm, cone of the oral disc 0,15 in height. Inner tentacles 0,35, 

 outer tentacles 0,2 cm. 



Occurrence: 70"4i' N. io°io' W. 263 fms. Temperature at the bottom -^- 0,3, brown clay with 

 stones. (Norw. North-Atl. Exp. 1877) i sp. 



Norway. Sunde, mouth of the Hardangerfiord proper (G. O. Sars) 2 sp. 



Exterior aspect: The indistinct pedal disc was extended, thin and membranous in the original 

 specimen, in one specimen from Sunde completely pulled off, in the other one (PI. i. figs. 17, 18) partly rather 

 much damaged, and the filaments of one side pressed out. Though the preserving of it was anything but 

 good, I do, however, tliink that I am able to decide that it was furnished with radial furrows. In sections 

 through the pedal disc deep incisions, where the mesenteries inserate, are namely to be observed. Daniels- 



