REPORT ON THE ACTINIAPJA. 89 



indistinctly denned rows. The tentacles of the innermost row are short, but broad at the 

 base, powerful and compressed; towards the outside the tentacles become smaller and 

 more slender. Indistinct radial furrows, caused by the distribution of the muscles, run 

 from the corona of tentacles to the oral opening. The muscles consist of tough, ecto- 

 dermal fibrilhe, the lamella made up of which lies thickly folded both in the oral disk 

 and in the tentacles. 



The oral opening is elongated to an oval in the same direction as the whole body of 

 the animal, and from analogy to other Actiniae we might expect to find the oesophageal 

 grooves at the ends of the oval. In this case, however, they lie exactly in the middle of 

 the two broad sides and in the contracted animal so near that they almost touch. If we 

 cut out the part in question (fig. 7, h) we see that the oesophageal grooves are very broad 

 and reach far down, whilst the remaining irregularly pleated part of the oesophagus only 

 hangs down a little way into the stomach. 



Except the two pairs of directive septa, which are attached to the oesophageal grooves, 

 the other four pairs of principal septa only are perfect, whilst all the secondary septa 

 terminate on the oral disk. The former are sterile, whilst the latter bear the repro- 

 ductive organs, which were testes in the specimen examined. There are large marginal 

 stomata in the septa, and in addition to these perioral stomata in the perfect principal 

 septa. 



I endeavoured to discover the mode of arrangement of the septa by cutting out two 

 sextants contiguous to the directive septa and making them into transverse sections. I 

 found extremely irregular conditions, and in spite of all my trouble I am unable to 

 explain them with any certainty. Five pairs of septa of considerable strength be in 

 each interseptal space, but as they were equal to one another I w r as not able to determine 

 their various ages from the difference in size. I am therefore undecided between two 

 opinions ; either the pairs of septa of the second order are doubled and three pairs of 

 septa of the third order are present, or else there is only one pair of septa of the second 

 order developed and the pairs of septa of the third order have undergone duplication. 



In the interseptal spaces of the third order I found either only a single pair of the 

 fourth order or two pairs of the fourth order ; so that duplication seems also to have 

 partially taken place here. 



It would be interesting to examine the sextants occupying the narrow side of the body 

 in order to see whether the arrangement of the septa is more regular in them. I refrained 

 from this, however, in order not to injure the single specimen of the species. We may, 

 however, certainly assume that the irregular development of the septa is the consequence 

 of the elongation of the body, and this is shown by the partial duplication of their number. 

 There would be nothing remarkable in such duplication, since the interseptal spaces 

 belonging to the broad sides are abnormally extended. 



(ZOOL. CHALL. EXP. PART XV. — 1882.) P 12 



