ZOANTHARIA 



37 



appearance and inner structure, that there can be no doubt that they represent 2 species quite different 

 from each other. 



var. jan mayeni PI. 2 fig. 2. 



Through the kindness of Prof. Marenzeller, I have had the opportunity of examining the 

 specimens from Jan Mayen which he considered Palythoa norvegica. They could not be referred to 

 this species with absolute certainty, but may well be considered as a variety of E, glacialis, from which 

 they differ but little, mostly with regard to the nematocysts which are generally somewhat larger than 

 in the main form. 



Occurrence. See above under the main form. 



Dimensions. Length of the largest polyp 1-2 cm., breadth in the capitular region 07 cm. 



Colour in alcohol. Ectoderm uncoloured. Mesogloea interspersed with black sand-grains. 



External appearance, i colony consisting 

 of 2 polyps, which lie close to each other projecting 

 from a thin ccenenchyme (fig. 2 PI. 2). In the con- 

 tracted state the polyps are elongated , cylindrical 

 somewhat broader at the upper end and with rounded 

 capitular region. The capitular furrows are very 

 distinct, in the smaller specimen I counted 21, in the 

 larger 24. The siphonoglyphe is well developed. 



Anatomical description. The ectoderm 

 of the body-wall is continuous, very high and thicker 

 than the mesogloca, in which we frequently find broad 

 nematocysts with greatly twisted thread (length 34 36^, 



Text-fig. 5. Transverse section through the body-wall with 

 adjacent mesenteries and cesophagus of Epizoanthus glacialfs 

 (specimens dredged by C. Nystroin). Mesoglcea and 

 muscles black. Ectoderm not drawn and entoderm only 



breadth 12 13/*). Incrustation of small Sand-grains. in part dc directive chamber. In the mesogloea of the 

 ,-,., ri ,, r body- wall the incrustations are marked by dots. 



Otherwise like the main form. 



While the spirocysts in the ectoderm of the tentacles were very numerous, the thick-walled 

 capsules only occurred in small numbers (length 24^). 



The ectoderm of the oesophagus has the typical appearance. The large nematocysts resembling 

 those in the body-wall are scarce but somewhat larger than usual (length 38 43//, breadth 12 i3y), 

 the thick-walled nematocyst capsules are numerous and longer than in the main form 26 29 

 (31)^ long. 



The mesenteries. The specimen examined has 42 mesenteries, 12 macro and 10 micro on the 

 one side, n macro and 9 micro on the other. Of the latter the ist proto-mesentery (according to the 

 developmental scheme adopted) was not much developed and very little larger than a micro-mesentery. 

 Otherwise the mesenteries are as in the main form. 



Ill the glandular tract occur some large nematocysts with much coiled thread (length 3436^ 

 breadth 13 p). Further, it contains fairly many thick-walled capsules with distinct basal part to the 

 spiral thread (length 2730^, breadth 



