26 



ZOANTHARIA 



This I have not observed and therefore think it probable, that another species has been concealed in 

 Danielssen's specimens - - such things have happened before — and been examined by H add on 

 and Shackle ton. Thus among the specimens of E. erdmanni from St. 42 collected during the 

 Spitzbergen Expedition 1898 there were many individuals which at first glance resembled E. erdmanni 

 (fig. 15, PI. 1) but actually did belong to another Epizoauthus species, i. e. E. daniclsscni. Also a 

 third Epizoanthus, E. beerenislandictts, was dredged at the same time. This latter species has lacunae 

 at the above-mentioned places. The entoderm is thinner than the ectoderm. 



The incrustation consists almost exclusively of sand-grains sometimes interspersed with a few 

 sponge-needles and foraminifera. Sometimes the incrustation in the mesoglcea is quite inconsiderable, 

 sometimes it fills up the whole, so that it is very difficult to study the structure of the latter. 



The sphincter is not long but strong and in the greater part of its course it covers almost 

 the whole breadth of the mesoglcea. In transverse sections through the sphincter the meshes are 

 large whereas the ridges of connective tissue between the muscle meshes are small (PI. 4, fig. 3). 



The tentacles have the usual structure. The ectoderm is provided with numerous spirocysts and 

 scarce thick-walled capsules (length about 17 (14—19)/;). The longitudinal muscles are fairly well-developed. 



The ectoderm of the oesophagus is fairly high and elongated. The large nematocysts of the 

 kind and size seen in the body-wall are scarce or absent, while the thick-walled capsules are numerous 

 and 19—24// long. The ectoderm of the siphonoglyphe is as usual somewhat lower than that of the 

 oesophagus, as the mesoglcea is thicker than in the oesophagus. 



The number of mesenteries varies between 28 and 40. Of the following 19 specimens 



2 specimens had 28 mesenteries (1 spec, was labelled E. arcticns, 



Komagfjord; see below). 



Thus, the most frequent numbers seem to be 32—34, which corresponds with the most frequent 

 number of capitular furrows. The specimens with 30, 34 and 38 mesenteries had a few mesenteries 

 more on the one side than on the other. The micromesenteries are fairly well-developed and project 

 into the gastric cavity, as long as the main part of the entoderm of the body-wall is high. The 

 longitudinal muscles of the macro-mesenteries are fairly well-developed, the mesoglcea is thin. The 

 parieto-basilar muscles are rather weak. The distribution of the longitudinal and the parieto-basilar 

 muscles on the body-wall is inconsiderable. 



Of the proto-mesenteric filaments the shortest are those corresponding to the 6th pair of proto- 

 mesenteries in Actiniaria, while the others are long. The filaments of the metamesenteries decrease in 

 length towards the siphonoglyphe. The filaments have the usual structure. Nematocysts with greatly 

 twisted thread resembling those in the body-wall occur sometimes very scarcely, sometimes more 

 frequently. They are equally broad and 24—31// long, the breadth being generally 10/z (9-12). The 



