122 



Prof. S. J. Hickson. 



separated generically from it. In a species described recently by Thomson 

 and Simpson* from the Indian Ocean under the name L. hicksoni, there are 

 no spicules in the tentacles. In a species described by Balss from Japan, 

 under the name L. hahereri, there are numerous spicules in the tentacles. 

 In other respects the two species are so much alike that it is difficult to 

 separate them, and, as regards the spiculation of the tentacles, we find an 

 intermediate condition in specimens from the Malay Archipelago, in which 

 spicules are occasionally present in the tentacles, but usually absent. In the 

 genus Veretillum spicules are said to be present in the anthocodiae of 

 V. cyTiomorium , but are absent in that position in the other four species. 



Similarly with respect to the presence of spicules in the cortex of the 

 rachis. A genus (Policella) was established by Grayf in 1870, and more 

 fully described by Kolliker in 1872. In Kolliker's description great stress 

 was laid on the character of the absence of spicules in the rachis, to 

 distinguish the genus from Veretillum. On making an examination of the 

 Gray's type specimen, however, he found a considerable number of large 

 spicules in the rachis. Marshall and FowlerJ found no spicules in the rachis 

 of two specimens of P. manillensis from the Indian Ocean, bxit a few 

 calcareous bodies in that position in a new species they named P. tenuis. In 

 a specimen from the Malay Archipelago, which in other respects closely 

 resembles the P. tenuis of Marshall and Fowler, I could find no trace 

 either of formed spicules or of calcareous bodies. With the failure of this 

 character, the genus Policella has become merged with Veretillum. 



No such wide variations as regards the variations in the distribution of 

 spicules are found in the higher bilaterally symmetrical Pennatulids. In 

 Pennatula, Pteroeides, or Seytalium, the presence of spicules in the rachis is 

 a constant character ; in Virgularia their absence is a constant character. 

 In any one species of the species that have spicules in the rachis, spicules 

 are either present or absent in the body-wall or the tentacles of the 

 anthocodise. Por example, spicules occur in the tentacles of P. naresi, 

 but do not occur in the tentacles of any one of the many specimens of 

 P. murrayi that I have examined. In S. halssii there are numerous 

 spicules in the body-wall of the anthocodiae and in the tentacles, but 

 in S. martensii, of which I have had over a hundred specimens to examine, 

 spicules are only found quite at the base of the body-wall, and never in the 

 tentacles. 



This character, however, is one that must be used with some caution for 



* Thomson and Simpson, ' Indian Alcyonaria,' Calcutta, Part II, 1909. 



t Gray, ' Catalogue of Sea-pens, British Museum,' 1870. 



I Marshall and Fowler, ' Trans. Eoy. Soc. Edinb.,' vol. 33 (1887). 



