108 THE VOYAGE OF H.M.S. CHALLENGER. 



Though Quatrefages, the discoverer of the Edwardsise (Mdmoire sur les Edwardsies, 

 nouveau genre de la famille des Actinies, Annales d. Sc. Nat. Zool., ser. ii. vol. xviii. p. 65, 

 1842), observed correctly that these Actinias have only eight septa, this important character 

 has not been sufficiently taken into account by most of the more recent writers. Milne- 

 Edwards and Gosse, who attach too much importance to the external characteristics of the 

 animal, had the absence of the pedal disk principally in view, and united the Edwardsise 

 with similar forms, Ilyanthus, Ccrianthus, &c, into the group of "Actinies pivotantes," 

 or the family of the Ilyanthidas. Allman was the first to draw attention in a short notice 

 (Quart. Jour. Microsc. Sci., new ser., vol. xii. p. 394, 1872) to the detached position of 

 the Edwardsise, as he maintained them to be forms which, in the distribution of the 

 septa, more closely resemble the Alcyonaria and the extinct Tetracorallia. My brother 

 and I have shown more recently, from a thorough anatomical examination of the posi- 

 tion of the septa (Actinien, pp. 124 and 137), that the Edwardsise occupy an intermediate 

 position between the larvse of the Actinise with eight septa and the Alcyonaria. In the 

 Alcyonaria the septa are arranged in such a way, that reckoned from one end of the 

 sagittal axis, all the eight septa (four left and four right) bear longitudinal muscles on the 

 faces turned away from the starting point, whilst in the larvse Actinise the first four only 

 (two left and two right) have longitudinal muscles on the faces turned away, and the 

 four following on the faces turned towards the starting point, so that we find the same 

 relative arrangement, whichever end of the sagittal axis we start from. In the Edwardsise 

 we meet with the number six and two, i.e., considered from one fixed end of the sagittal 

 axis the first six septa are constituted like those of the Alcyonaria, the last two like 

 those of the Actinise. As in the Actinise the two pairs of septa jjlaced one at each end 

 of the oral fissure form the directive septa, two pairs of the directive septa are therefore 

 likewise present in the Edwardsise. 



The correctness of the view, briefly recapitulated above, has been further corroborated 

 by a newly published work of Angelo Andres (Intorno all' Edwardsia Claparedii ; Mittheil. 

 der zoolog. Station zu Neapel, Bd. ii. p. 123) ; at the same time he pronounces in favour 

 of Allman's view that the Edwardsiaa may bear the same relation to the Tetracorallia as 

 the Actinise do to the skeleton-forming Hexacorallia. I do not agree with him on this 

 point. Apart from the number of the calcareous septa, the formation of the skeleton 

 is the same in the Hexacorallia and Tetracorallia, and it is therefore probable that similar 

 relations have existed among the soft parts of the body, and that the paired arrangement of 

 the septa was already developed in the Tetracorallia. As this is not the case in the 

 Edwardsise, I am inclined to seek for points of connection with the Rugosa in such forms 

 as Sicyonis crassa. 



There was no true Edwardsia among the Challenger material ; but I was long 

 duboius as to whether it might not be expedient to include among them those forms in 

 which the paired arrangement and the number twelve of the septa begin to be developed, 



