ACTINIARIA 



siphonoglyphes with no aboral prolongations or with short ones. Mesenteries in those cycles (6 + 6+12 

 pairs) more numerous than the tentacles. Longitudinal muscle-pennons rather strong, broad. Parieto- 

 basilar muscles very strong almost reaching the sphincter. Oral stomata but no marginal stomata. Dioecious. 

 6 symmetrically placed pairs of the mesenteries of the last cycle without filaments and reproductive organs. 

 The embryos develop in excavated pits on the outside of the aboral part of the column. Nematocysts in the 

 ectoderm of the column 29 37 X 2,5 3 p, in the tentacles 24 30x2 2,5 p, in the actinopharynx (26)29 

 36 X 3 3,5 ft. Spirocysts of the tentacles 19 x i // to 34 x 2,5 p. 



Colour in alcohol: In a specimen the ectoderm of the column was dark brown especially in the distal 

 part, and sprinkled with small white spots. Another specimen was more light brown, and a third in the distal 

 part dark brown (in the proximal part the ectoderm was lost). The ectoderm of the column in the other 

 specimens was uncoloured, here and there fragments of darker parts (cuticle?) were however present. 



Dimensions: A specimen, the column of which was much expanded, measured in height and breadth 

 3 cm. The largest specimen with involved tentacles and of a cylindrical-conical appearance was 3,4 cm long 

 and 2 cm broad. The smallest specimen with visible tentacles was 2,1 cm long and 0,9 cm broad. 



Occurrence: 6453' N. ioo' W. 630 m. Temp, at 600 m 0,69 (Michael Sars-Exp. 1900). 



Arctic ocean north of Behring's strait 30 fms. (North Pac. expl.-Exp. teste Verrill). 



Exterior aspect. Of the 10 specimens three were comparatively slightly contracted. Their column 

 was cylindrical and their tentacles unfolded. Four specimens were strongly expanded, their breadth and height 

 about equal, the form of the others was like a drawn-out cone. The pedal disc was well-developed. The 

 column was in the contracted specimen often a little longitudinally wrinkled. In a specimen, the colour of which 

 was the best preserved, there were small, light, irregularly scattered spots, the largest spots appeared in the 

 distal part, though also there they were almost inconspicuous to the naked eye; the smallest spots, scattered 

 between the larger, and especially very numerous in the lower part of the column, were only conspicuous 

 under strong magnifying powers. Traces of such spots were present also in another specimen. Some of 

 the others show fragments of a thick cuticle (compare below). Near the base of an expanded specimen there 

 were several large circular spots reaching those I have observed in a specimen of E. marsupialis. In this 

 species the spots were certainly marks of embryos, having evidently passed some time upon the parent after 

 emigrating from their brood-rooms. From this I conclude that also this specimen of E. arctica has been fur- 

 nished with brood-rooms. The fossa was distinct. The tentacles were conically drawn out, between 31 and 38 

 in number, hexamerously arranged, the last cycle was imperfect. Commonly they were smooth, sometimes 

 a little longitudinally sulcated. The number of the tentacles was smaller than that of the mesenteries. The 

 actinopharynx was long and furnished with at least 24 longitudinal ridges, sometimes more. The two sym- 

 metrically placed siphonoglyphes show distinct gonidial tubercles, I am not able to find any perspicuous 

 aboral prolongations. 



Anatomical description: The ectoderm of the column is high and contains very numerous 

 nematocysts, which are longer than those of the actinopharynx. Their size variates between2g 37 X 2,5-3 /" I n 

 a specimen I found a capsule, 43 X 4,5 u in size. The above named small spots on the column of the best preserved 

 specimen display another structure than the other parts of the body-wall. They are built up mainly of support- 



