ACTINIARIA 



Hertwig (1879) and by Appellof (1891), but in several respects imperfectly. Neither is my description as 

 perfect as desirable, the material not always having been well preserved. 



The ectoderm of the scapus is considerably thinner than the mesogloea. The nematocysts of the 

 nemathybomes are numerous and of two kinds, both long, but one much more thin than the other. The longer 

 and broader ones are a little thicker at the basal end, gradually tapering towards the distal end. In these 

 latter the basal part to the spiral thread is commonly discernible. 



The size of the nematocysts (n) and the spirocysts (sp.) in the different parts of the body is seen 

 on the following table. 



n(a) typical nematocysts, n(b) nematocysts with a conspicuous basal part to the spiral thread. 



As we see, the size of the stinging capsules agrees in the different specimens. Only in the specimens 

 7 and 8 the nematocysts of the nemathybomes are shorter; these specimens were also about half as long 

 (length i.i cm, breadth 0.3 cm) as the others. Also in the smaller specimens the larger nematocysts of the nema- 

 thybomes reach a length of more than 100 // (compare Edw. longicornis). Whether the n(b) -capsules, which 

 are broader in the basal end, are constant, I cannot decide, I have not observed any in the specimens i and 2. 

 In the maceration preparations of the two "Thor"-specimens, the ectoderm of which was very badly preserved, 

 I found only one smaller nematocyst and 8 larger in the fragments of the nemathybomes. There is, however, 

 no doubt that these specimens are E. tuberculata, as the muscles of the mesenteries agree with those of the 

 specimens from Norway. 



The 8 "Edwardsia-mesenteries" have strong pennons. O. and R. Hertwig (1879) have given a 

 reproduction of a mesentery in the reproductive region. Owing to the comparatively few muscle-folds of the 

 pennon the mesentery has probably been sectioned in the lower part of this tract, or the section possibly 

 belongs to a smaller specimen. The textfigure 12 shows a section of a pennon in the upper part of the repro- 

 ductive region. The pennon is rather elongated, the highest folds as usual next to the outside. The about 30 

 folds are mostly high, the high folds often dichotomously branched. The most ramificated fold is as usual 

 the outermost. The parietal muscles are very high, the folds for the greater part dichotomously branched 

 and issuing almost perpendicularly from the thick, main lamella (textfig. 14). For comparison I have here 

 also reproduced figures of a pennon (textfig. 13) and of a parietal muscle (textfig. 15), belonging to a young, 

 not sexually ripe specimen. The folds of the muscles are here considerably fewer. The extension of the parietal 

 muscles on the column is inconsiderable. 



