ZOANTHARIA 



49 



capitular region light. In the living condition: ccenenchyme and the proximal part of the polyps 

 brown, disc brown frequently with white radial stripes (Mortensenl. 



External appearance. The ccenenchyme consists of an irregularly branched network with 

 a thin attachment to dead oyster-shells. The polyps emerge from the ccenenchyme sometimes at smaller, 

 sometimes greater intervals. They are small, cylindrical and when much contracted almost as high as 

 broad or the breadth is a little larger (PI. i, fig. 4), in less contracted state (PI. i, fig. 3) they are twice 

 as high as broad. In the contracted state the distal part is rounded. The capitular furrows are indistinct 

 on the not very well preserved material, so that their number cannot be given. 



The oesophagus is short, the siphonoglyphe distinct, but the hyposulcus seems to be short. 



Anatomical description. The ectoderm of the body-wall is moderately developed and as 

 far as I am able to see continuous (owing to the strong contraction and the folding resulting there- 

 from it is difficult to determine this with certainty). It is incrusted with coarse sand-grains, some 

 sponge-needles and detritus, in which numerous diatoms occur. The ectoderm contains uniformly broad 

 nematocysts with greatly twisted thread (length 22—26^, breadth generally 7 sometimes 10//). Whether 

 they are numerous or not I am unable to say for certain. The mesoglcea is moderately developed, 

 the outer part incrusted, it has no lacunae and very few cells (cell-islets) which sometimes lie in groups 

 close to each other. The cells are however so scarce that the mesoglcea looks almost as if it was 

 homogeneous and cell-free, this being fairly characteristic of the species (PL 7, fig. 4). The entoderm 

 is of moderate thickness and contains fairly many zooxauthellae, which besides occur everywhere in 

 the entodermal layer of the polyp. 



The sphincter is entodermal, somewhat folded at the upper part and fairly long in consideration 

 of the small size of the animal. The musculature is strong so that the capitular region is very much 

 retracted in the contracted state. 



The structure of the oesophagus seems to be the same as in the other Zoanthidae. The ectoderm 

 is high, the mesoglcea thin. I have not been able to make any macerated preparations of the oesophagus, 

 because this is so short and folded and badly preserved. The siphonoglyphe has a somewhat lower 

 ectoderm than the oesophagus, and the mesoglcea is a little thicker than in the oesophagus. 



In 7 specimens examined the number of mesenteries were 18, 20, 20, 20, 22, 24, 24; the spec- 

 imens with 18 and 22 mesenteries had 1 couple of mesenteries more on the one side of the body than 

 on the other. It is difficult to see the arrangement, as the specimens especially in the oesophageal 

 region were badly preserved. It is worth noticing especially, that the sixth conple of proto-mesenteries, 

 i. e. the proto-mesenteries lying nearest to the meta-mesenteries, as also the macro-meta-mesenteries, 

 have not yet grown out to the oesophagus and had no filament (at least not in the specimen with 18 

 mesenteries). The sixth couple of proto-mesenteries, the micro-proto-mesenteries and all meta-mesenteries 

 seem to be almost equally developed. Though it might be supposed, that the polyps were brachyenemic, 

 it is however probable, that they are macrocnemic, though the 6th couple of proto-mesenteries have 

 not yet reached the oesophagus. This is also indicated by the small development of the macro-meta- 

 mesenteries. The micro-mesenteries at any rate are well-developed. The longitudinal musculature is 

 strong on the complete mesenteries, especially on the directive mesenteries, where it forms deep folds. 



The Ingolf-Expedition. V. 4. 7 



