494 SYDNEY J. HICKSON. 



1. Sub-genus Sclerosolenocaulon. 



Solenocaulon tubulosa, Genth. 

 Solenocaulun sterroklonium, Germ. 

 Solenocaulon diplokalyx, Germ. 



2. Sub-genus Malacosolenocaulon. 



Solenocaulon tortuosum, Gray. 

 Solenocaulon akalyx, Temate. 

 Solenocaulon grayi, Studer. 



A careful consideration of Germanos' laborious investigation in the light thrown upon 

 the subject by Mr Gardiner's fine collection and the type specimens in the British Museum 

 has led me to the conclusion that this arrangement of the species is not satisfactory. The 

 first and most important character that is used by this author for the separation of the 

 sub-genus Sclerosolenocaulon from Malacosolenocaulon is the presence of a stalk. It appears to 

 me to be still a matter of doubt whether there are any specimens of Solenocaulon without 

 a stalk, since the original specimen described by Gray certainly has a stalk, which is solid, 

 and the specimen attributed to the same genus by Studer was incomplete at the base, and 

 therefore atforded no evidence on the subject. The specimen upon which Germanos bases 

 his species S. akalyx consisted only of "zwei gi-osse Stiicke," and as no description, figure, 

 or even statement is given of the base of attachment, it is reasonable to suppose that it 

 was missing. The stalk is also missing in the only specimen that has hitherto been described 

 of the species S. grayi, Studer. It is difficult to understand how Germanos could have over- 

 looked these facts in drawing up his classification, unless it is supposed he uses the word 

 stalk " Stiel " in a sense which is not usual. As regards the character of the axis which 

 plays an important part in this classification, I may say that Studer's description of the 

 axis " aus durch Hornmasse verbundenen, losen, .spindel-formigen Spicula bestehen " accurately 

 describes the axis of Mr Gardiner's specimens. I cannot understand what is meant by the 

 statement that in the branches of Solenocaulon tubulosa, S. sterroklonium, and S. diplokalyx 

 the spicules are fused to form a solid axis. If we are to understand that the calcareous 

 spicules are fused together to form a solid calcareous rod as in the axis of Corallium or 

 the tubes of Tuhipora, then it may be regarded as a character of specific or even of sub- 

 generic importance, but Germanos brings little evidence to prove that this is the case. In 

 many of the smaller branches of my specimens I find the spicules of the axis so tightly 

 packed together as to form a porous calcareous rod as figured by Genth, which does not 

 break up on boiling in 5 °/„ potash, but as Genth adds, " Die verschmolzenen Spicula gehen 

 ohne merkliche Grenze in die freien liber." Whether the spicules do or do not become so 

 tightly packed as this in the branches depends upon the rapidity of growth of the indi- 

 vidual branch, and is not of the slightest systematic importance. If the spicules fused in 

 some forms to form a solid axis in the stem or stalk and not in others, we should have 

 a character of prime importance, but the axis of the stem and stalk is admittedly the same 

 in all species. 



The species Solenocaulon tortuosum Gray and Solenogorgia {Solenocaulon) tubulosa Genth 

 differ from one another principally in the fact that the latter gives off from the main 

 tubular stems several short grooved blunt branches bearing numerous anthocodiae. In the 



