526 



On Arachnactis brachiolata. 



central wall to the periphery, as transparent lamella3 

 reaching, as in Edwardsia* but a small distance from the 

 Fi^r, 2. actinal region towards the abacti- 



nal side. Fig. (2.) The partitions 

 corresponding to the first-formed 

 tentacles remain always larger and 

 more prominent than the others. 



When seen from different sides 

 the aspect of this actinia is very 

 different. It exhibits to a remark- 

 able degree bilateral symmetry. 

 When seen from above we can 

 see at once, even in young speci- 

 mens in which there are not more 

 than four tentacles, that the slit 

 of the mouth is not placed in the 

 centre of the disk, but nearer one 

 '"'" edge, (fig. 3.) and that the tenta- 

 cles are not arranged in circles round 

 the mouth, the largest nearest the 

 mouth slit. On the contrary, the 

 tentacles are arranged in two simple, 

 independent rows, one row surround- 

 ing the mouth slit, and the other ar- 

 ranged precisely in the same way on 

 the edge of the disk. The mode of de- 

 Disk seen from above. Yclopmcnt of thc tcntaclcs is sucli that 

 the youngest, the smallest, last- formed tentacles, either 

 round the mouth or round the disk, are always placed at 

 one end of the mouth slit. It is there that additional ten- 

 tacles are formed, and not in the intermediate spaces be- 

 tween the first tentacles. Unlike otiier Polyps, the tentacles 

 of thc first cycle are not developed at the same time, but 



* Quntn-fagcs, A. dc, Mcmoires sur les Kdwardsies, (Edwardsin,) nouveau genre 

 de la famille dcs Actinies. Ann. Sc. Nat. 1842, Vol. xviii. p. 65. 



Ararhnfirtis hrar/iinldta^ iiaritiw tiiUi 

 facing pair of teiitacU' 



Ki'.'. .S. 



