X.OAXTHARIA 



in large groups that may occupy as much space as a closed hand, wherein more than 50 polyps are 

 attached by the same coenosark." 



The number of tentacles corresponds to the number of mesenteries, being thus in larger 

 specimens considerably greater than stated by Koren and Danielssen. 



The oral disc is wide, the mouth lies on a cone, the mouth-opening is like a slit. 



The oesophagus is short and the siphonoglyphe well-developed with distinct hyposulcus. 



Fission. On the colony taken by Storm in Skarn Sound I observed a double polyp in the 

 middle part. (PL 2 fig. 22). Almost the whole of the body-wall was continued smoothly without boundary 

 from the one polyp to the other, but the ridges and for the most part also the capitular furrows could 

 be seen in each polyp. The one polyp had 20, the other no less than 24 ridges and furrows. Each polyp 

 had its special circlet of tentacles fully separated. How far a doubling of the tentacle takes place 

 from the directive chamber, I am unable to say, as I did not wish to cut up the polyp completely 

 but there is probably a directive tentacle on each polyp. Each polyp has its distinct oesophagus and 

 siphonoglyphe, but a common directive chamber. The cleavage has thus taken place in the directive 

 chamber. This condition has some resemblance to the double formations in Cribrina gemmacea 

 previously described by me (Studien iiber Regenerations und Regulationserscheinungen. K. Svenska 

 Vet. Akad. Handl. B. 37 1904 p. 82 text-fig. 13, PL 2, fig. 21), of course with the difference caused by 

 the different organisation of the two groups. 



Anatomical structure. Haddon and Shackleton (1891) have given some information 

 regarding the anatomical structure of this species. They state that the ectoderm, the mesogloea and 

 the entoderm of the body-wall reach a considerable size and that numerous nematocysts are found in 

 the ectoderm. Furthermore, they point out that the micromesenteries are strongly developed. In 

 their paper we find a figure showing a section of the body-wall evidently from the capitular region. 

 Otherwise this species has not been subjected to any anatomical examination. 



The ectoderm of the body-wall is very thick and discontinuous (PL 5, fig. 3) except at the 

 capitular region (PL 5, fig. 2), though the discontinuity is hardly so conspicuous as in Epizoanthus 

 paguriphilus. It contains numerous nematocysts with greatly twisted thread, which have a length of 

 2429;* and a breadth of I2//; they are oval and almost equally broad at both ends. Haddon and 

 and Shackleton state that they contain pigment granules. This is however doubtful; I think it 

 probable that small air-bubbles have penetrated into the nematocysts in sectioning and that these 

 bubbles have been mistaken for granules. This often happens and I have had the same experience 

 with many Zoantharia, Ceriantharia and Actiniaria. The mesoglcea is considerably thicker than the 

 ectoderm and now and then runs out into outshoots which cut off parts of the ectoderm from each 

 other and even end in the cuticle, though without forming such small, closed spaces as in Epizoanthus 

 paguriphilus. The mesogloea contains fairly many cells with outrunners, now and then cell-islets and 

 very seldom ectodermal lacunae. The entoderm of the body-wall reaches a considerable size. The 

 incrustation in this species is inconsiderable and lies mostly in the ectoderm and in the outer parts 

 of the mesoglcea, consisting of sand-grains, foraminifera and sponge-needles. 



The sphincter is strong, mesogloeal and finely divided. The meshes in transverse section are 

 drawn out in a transverse direction. The sphincter lies nearer the ectoderm than the entoderm, so 



3* 



