36 



ZOANTHARIA 



The tentacles have the usual structure. The spirocysts in the ectoderm are as usual very 

 numerous, the thick-walled ones (17—22, 19—24 /i long) scarce. Further, some large nematocj-sts of 

 the same kind as in the body-wall occur in very small quantities. The longitudinal musculature is 

 moderately developed. 



The ectoderm of the oesophagus is liigli. It contains fairly great numbers of nematocysts partly 

 large with much coiled thread and uniformly broad, length (26) 29 — 36, «, breadth about 12//, partly 

 thick-walled 19 — 24^1 long. The mesoglcea is thin but that of the siphonoglyphe on the other hand is 

 considerably thickened. The ectoderm of the siphonoglyphe is as usual thinner than in the reso- 

 phageal region. 



The number of mesenteries varies according to the size of the polyps, 3 of the examined Umenak 

 specimens had 40, 46 and 50 mesenteries. The arrangement of the mesenteries in the first polyp was 

 typical, both the others had a pair of mesenteries more on the one side of the directive chamber 

 than the other. One of the type specimens (the smallest) had 36, another 40 and a third no less than 

 52 mesenteries. While the first and last polyp were symmetrical the third one was very asymmetrical, 

 the one side having 22, the other no more than 18 mesenteries. Specimens from Oxfjord Finmarken 

 had 36 mesenteries. Danielssen's .statement that the number of micro-mesenteries is the same as 

 the number of macro-mesenteries is of course incorrect, as Zoanthidae-species with the mesenteries 

 arranged according to the macro-type do not have as many micro as macro-mesenteries. 



In the esophageal region the macro-mesenteries are fairly thick with well-developed mesoglrea. 

 The longitudinal musculature is strong with fairly many folds (text-fig. 5). The parieto-basilar muscles 

 are weak. Extension of the longitudinal and parieto-basilar muscles onto the body-wall inconsiderable. 

 In the sexual region the macro-mesenteries are thin and the musculature weak. The micro-mesenteries 

 are moderately developed. 



The structure of the filaments is as usual. The glandular tract sometimes contains greater 

 sometimes smaller numbers of large, uniformly broad nematocysts with much coiled thread — length 

 (26) 29— 36/i breadth 10—13/^ — and thick-walled capsules 19— 26 /i long with distinct ba.sal part to 

 the spiral thread. 



The species is dioecious. 



Systematic remarks. In the samjile from St. 164 Norw. North Atl. Ex., — the only type- 

 specimens of E. glacialis which I have had for examination, — there were two .species which have 

 undoubtedly been mixed in Danielssen's description. The one is the species described here, which 

 I have considered the type-specimen of Danielssen's species glacialis, as his description, at any 

 rate with regard to the external appearance, may in the main be referred to this species. Figures 7 

 and 8 on PI. 6 in Danielssen's work evidently represent the above-described species and the .same 

 is certainly the case with fig. 5 and probably also with fig. 6 on PL 24. On the other hand, fig. 9 

 PI. 6 probably represents E. danielssem. With regard to the anatomical figures of E. glacialis in Da- 

 nielssen's work they are .so poor that they may represent the one as well as the other of the species, 

 though the weak incrustation seems to indicate the species I have described as glacialis. Both species 

 are namely so unlike each other, not onl)- with regard to the nematocysts but also in external 



