ZOANTHARIA 33 



Epizoanthus beeren-islandicus n. sp. 



PI. 2, fig. 10, PI. 3, fig. 2, PI. 4, fig. i. 



Occurrence: 73 3' N., i83o'E. Beeren Island-Norway 410 m. Bott. temp. 2. Gray clay. Spitz- 

 bergen Exp. 1898 4/9. No. 42 3 sp. R. M. 



Dimensions of the largest polyp: height and breadth about i cm. 



Colour in alcohol: yellowish. 



External appearance. The three specimens of this species formed no colonies. One 

 was attached to a stone, one other to a Retepora. The coenenchyme was very thin, disc-shaped. 

 The polyps are cylindrical, almost as high as broad - - the animals however were very contracted - 

 and the distal part was a little broader than the proximal. The upper margin was truncate on the 

 contracted polyps. The capitular region has some fairly distinct furrows. In the large specimens I 

 counted 21 capitular furrows with distinct, incrusted ridges between them. The incrustation, which is 

 comparatively inconsiderable, consists of small light sand-grains, now and then interspersed with a few 

 small black sand-grains. 



The oesophagus is short with distinct siphonoglyphe and hyposulcus of almost the same length 

 as the oesophagus. 



Anatomical description based on two specimens. The ectoderm of the body-wall is con- 

 tinuous and provided with a distinct cuticle. It is fairly high and contains nematocysts with greatly 

 twisted thread, which are uniformly broad, 31 37^ long and n 12 // broad, and fairly common except 

 in the capitular region. The mesogloca is always thicker than the ectoderm, double as thick at the 

 most. It contains fairly many small cells with long thread-shaped outshoots, here and there cell-islets 

 and lacunae. The latter often, though not always, lie at the base of the mesenteries, so that in certain 

 sections (PI. 4, fig. i) the lacunae are very characteristic in appearance. The eutoderm is almost of the 

 same size as the ectoderm. The incrustation is rather inconsiderable in the ectoderm; the greater part 

 of the mesogloca has no incrustation, this is mostly found near the mesenteries from which it often 

 penetrates into the above-mentioned lacunae. 



The sphincter is strong and long (PI. 3, fig. 2) and lies nearer the ecto- than the entoderm , so 

 that in the capitular furrows it is only separated from the ectoderm, by a thin mesogloeal lamella. 

 The muscle-meshes are drawn out crosswise and the mesogloeal meshes are thin. 



The ectoderm of the tentacles contains as usual numerous spirocysts, whereas the thick-walled 

 nematocysts (length 17/4) are very scarce. Further, there is a very sparse occurrence of the same 

 large nematocysts as found in the filaments. The ectodermal musculature is fairly strong. 



The ectoderm of the oesophagus contains fairly many large nematocysts (length 34 41 ft] and 

 numerous typical, thick-walled capsules (length 22 25//). The structure of the siphonoglyphe agrees 

 with that in other species of Zoanthidae described here. 



The number of mesenteries in the three specimens was 44, 40 and 39 respectively. In the first 

 specimen, which was regularly developed, the 6th proto-mesentery on the one side of the sagittal plane 

 was a micro instead of a macro-mesentery. In the second specimen the one side was more developed 

 and had one pair of mesenteries more than the other. The micro-mesenteries in the lower part of 



The Ingolf-Expedition. V. 4. 5 



