ACTINIARIA 



217 



ally some of the smallest mesenteries of the third cj-cle bear reproductive organs. This is the case with the 

 pairs 5 and 29 of the specimen 2, and the pairs 2, 23 and 25 of specimen 5 ; in the latter specimen they agree 

 with the other fertile mesenteries, in the former they were provided with filaments. 



The longitudinal muscles of the mesenteries are well-developed with closely packed , high folds , expanded 

 over the whole surface and not forming pennons. The parietobasilar muscles are well marked, broad in the 

 lower part and reaching far upwards as a narrow lamella, their folds are, however, ver\' weak in the lower 

 part, in the upper part the muscles form an even lamella. The mesogloea is thick in the stronger mesenteries, 

 thin in the fertile. The greater part of the latter is occupied by the reproductive organs, only a little part next 

 to the column is muscular. The muscle folds are also here numerous on the longitudinal muscle-side, so that 

 we may say that the muscles of the fertile mesenteries form a miniature of those of the sterile mesenteries. 

 Oral stomata are present. The stronger mesenteries are also generally provided with marginal stomata. 

 The filaments of the sterile mesenteries are of typical appearance, the ciliated streaks are well-developed. 

 The fertile mesenteries, excepting the above named, are completely devoid of filaments, as far as I can see, 

 wliich is in conformity with Hertwig's observations of the type-specimen, 5. crassa. The species is dioe- 

 cious. The ova are numerous but small. 



Sicyonis ingolfi n. sp. 



PI. 3. I'ig. I. 



Diagnosis: Body rather low. Column in the uppermost part with longitudinal furrows. Sphincter 

 as in the former species feeble with a tendency to stratification. Tentacles about 68, the outer with large, 

 the inner with weak, abaxial, bulbous thickenings at the base. Apertures in the apex of the tentacles small. 

 Longitudinal muscles of the tentacles and radial muscles of the oral disc as in 5. tuberculata, only feebler. 

 Actiuopharynx and siphonoglyphes as in the former species. Pairs of mesenteries 68, 34 with well developed 

 filaments and rather well developed muscles, sterile, 34 without filaments, fertile, only present in the proximal 

 part of the body. 16 pairs perfect. Both mesenteries of the same pair of the other stronger mesenteries some- 

 times unequally developed, so that one mesentery is perfect, the other not. Muscles of the mesenteries about 

 as in S. tuberculata, but feebler. Oral and marginal stomata present, the latter at least on some of the stronger 

 mesenteries. Nematocj'sts in the ectoderm of the tentacles 36 — 41 x 2,5 n, in the actiuopharynx 29 — 36 

 (38) X about 3 fi. Nematocysts with discernible basal part to the spiral thread in the actiuopharynx 26 — 29 

 X 5 ;/. Spirocysts of the tentacles from 24 X 2 ;/ to 62 X 4 /u. 



Colour in alcohol: white, the actiuopharynx uncoloured. 



Dimensions in contracted state: I^ength 3 cm, breadth 4 cm. 



Occurrence: South of Greenland. 58°2o' N. 48°25' W. 1695 fms. Bottom temp. i°5 (Ingolf-Exp. 



St. 20) I sp. 



Exterior aspect. The exterior of this species (PI. 3 fig. i) recalls that of 5. tuberculata. The 

 longitudinal furrows in the uppermost part of the column are more distinct, as in this species. Only the outer 

 tentacles are provided with strong mesogloeal thickenings on the abaxial side, the inner tentacles are also 

 here a little thickened, though by far not as much as in the former species. The tentacles are closer than in 



The Ingolf-Expedition. V. 9. -g 



