ACTINIARIA 



somewhat sparser, their size is commonly 24 29 X 5 //, rarely unto 36 x 6 fi. Besides these, I have here 

 found sparse, sometimes a little curved, nematocysts of about 29 X 3 // in size. 



The mesenteries are hexamerously arranged in three cycles, 6 + 6+12, the latter cycle is imper- 

 fect. There are two pairs of directive mesenteries. The first six pairs are perfect and provided with well 

 developed filaments with ciliated streaks. The six pairs of the second cycle are imperfect and of full body- 

 length like the mesenteries of the first cycle, at least several of the mesenteries of the second cycle bear distinct, 

 although not long, filaments. The mesenteries of the third cycle are very weak and only rising a little over 

 the endoderm of the column. Only the first six pairs have pennons ; the sixth pair the ventral mesenteries 

 of the ventro-lateral pairs is the weakest. The longitudinal pennons are much stronger than in A. inte- 



Fig. 122 



Fig. 123 



Fig. 124 



Textfigs. 122 124. 

 Acthelmis schaudinnii. 



Fig. 122: Transverse section of pennon in the lower 

 part of the actinopharynx. Fig. 123: A similar sec- 

 tion in the reproductive tract. Fig. 124: Transverse 

 section of a mesentery of the second cycle. 



stinalis. The folds are high and rather richly ramificated. A transverse-section of a pennon in the lower region 

 of the actinopharynx of the specimen from Great fiord is reproduced in the textfig. 122. (The side of the 

 actinopharynx is turned upwards) . In the tract of the reproductive organs the folds are very high and partly 

 much ramificated (textfig. 123, transverse-sections of the specimen from Great fiord). The parietal muscles 

 are weak, the folds are thick, few and low, and recall those of the muscles of the mesenteries of the second 

 cycle, though the folds are stronger here. The mesogloea is strongly developed in the parietal muscle-tract 

 as well as in the mesenteries of the second order, wherefore these part in transverse-sections are of a more 

 robust appearance than the corresponding tracts of A. intestinalis. (The textfigure 124 shows a transverse- 

 section through a mesentery of the second order of a specimen from New-Zembla). The parietal muscles 

 seem to be sparsely spread over the column. Stomata are probably present in the distal part of the mesen- 

 teries. Only the first six pairs of mesenteries bear reproductive organs. The specimen is dioecious. 



Remarks: The state of preservation of the specimens was not good, wherefore the description is 



