ACTINIARIA 



225 



part of the specimens there were large specific nematocysts of the 

 same kind as I have found in the other, below described Actinostola 

 species. These capsules were now numerous, now sparse. I at first 

 supposed that I had to do with two different species, one with large 

 specific nematocysts, the other without such, as there is, however, 

 no difference in their structure I must regard these specimens as 

 belonging to the same species, the more so as I have found some 

 specimens, the nematocysts of which were so sparse that it was 

 only after repeated examinations of the maceration preparations 

 that I was able to find one or a few capsules in the tentacles. I can- 

 not decide the cause of this difference in the occurrence of these ne- 

 matocysts. It may be possible that they have in several cases been 

 lost through preservation, though I must confess that I do not find 

 that explanation satisfactory. In the actinopharynx there are, in 

 addition to typical nematocysts, also some such with discernible 

 basal part to the spiral thread. The size of the nematocysts and 

 the spirocysts in a series of specimens was as follows, a: typical 

 nematocysts, b : large specific, opaque nematocysts, c : nematocysts 

 with discernible basal part to the spiral thread, spi: spirocysts. 

 As wee see, the nematocysts of the dififerent specimens agree 

 well in size, it is therefore probable that the specimens with b-ne- 

 matocysts in their tentacles and those devoid of such belong to 

 the same species. The sphincter also varies a little in appearance. 

 In the type-specimen it was strongly concentrated, in other spec- 

 imens more elongated, as in Stomphia. As we may find a concen- 

 trated as well as an elongated sphincter in different parts of one 

 and the same specimen, I think that this difierence is due to a 

 stronger or weaker contraction of the mesogloea in the distal part 

 of the column. In the type-specimen the spliincter occupies almost 

 the whole breadth of the mesogloea, which was also the case in se- 

 veral examined specimens. In other specimens the part of the me- 

 sogloea, outside of the sphincter, was considerably tliicker, this is 

 especially the case in specimens having a tliick mesogloea. Tliis dif- 

 ference is jDrobably also connected with the more or less strong con- 

 traction of the mesogloea. The sphincter also varies a little in 

 structure. Generally the spliincter is reticular, sometimes, especially 

 in the outermost parts, the meshes are more sparse, wherefore the 

 sphincter here shows a tendency to be alveolar. To judge from the 



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