FEOM THE INDIAN AND PACIFIC OCEANS. 23 



generally four spicules in the points of the anthocodite arranged "en chevron" ; but the 

 complete retractility of C. siphonogorgica and C. retractills and the armature of the 

 polyps of C. dipsacea show that the characters are not infallible. Therefore until 

 a series of intermediate forms is described it will be found convenient to distinguish 

 Chironephthya from Slphonogorgia by the mode of branching of the canal-system. This 

 is the course I have adopted in the present report, and in the systematic part will be 

 found the necessary readjustment of the already-described species. 



With regard to the genus Solenocaulon, Janower (22) has given such an excellent 

 historical review that I need only here refer to it. 



Of the four Solenocaulons in this collection, one is undoubtedly Hickson's new 

 species S. ramosum * and calls for no special comment. The other three form an 

 interesting series, and as I believe them to be all the same species I shall refer to them 

 as A, B, and C. The first most noticeable feature common to all three specimens is 

 that they are unbranched — that is to say, that each colony consists of a single straight 

 hollow main trunk which gives off small lateral twigs, with polyps borne both on the 

 twigs and the main trunk; there is no extensive branching such as Janower figures in 

 tne pnoiograph of Gray's original S. tortuosum (22) or Genth's figure of S. tubulosum (1 1 ). 

 The second striking feature is the retractility of the polyps. In A they are very 

 much expanded, a conical calyx projects from the smooth surface of the main trunk 

 or twig, and the polyp-heads project conspicuously beyond. In B the same thing 

 occurs, but not so markedly. In the flattened tubular nature of the little branches 

 both these forms resemble S. tubulosum (Genth). In C the polyps are completely 

 retractile, and only a very slight elevation marks their position externally. In this 

 and in the solid grooved appeai'ance of the twigs the colony resembles S. tortuosum. 



With regard to the solid axis about which there has been so much controversy : in 

 A and B there appears to be a " porous calcareous rod .... which does not break up on 

 boiling in 5 % potash." This is shown in text-figs. 5 and 6. Text-fig. 5 is a transverse 

 section through the main trunk, and text-fig. 6 a transverse section through a terminal 

 twig ; in both this porous rod is obvious. It is absent in the stalk, of which a quadrant 

 is shown in text-fig. 7. When Germanos (12) made his classification, in which he relied 

 so much on the presence or absence of a " solid axis," I doubt that he ever meant to 

 imply more than a " porous rod," such as is shown to exist in the present specimen. 

 Turning now to specimen C, which outwardly resembles S. tortuosum, the circumstances 

 are different, for here the '■ porous rod " is not continuous, but appears to consist of 

 a series of calcified centres in which the spicules are fused together as in A and B, 

 alternating with tracts in which the spicules are disposed quite loosely in the coenencliyme. 

 This is shown by a comparison of text-figs. 8 and 9, which are two sections from the 

 same series : text-fig. 8 is a transverse section through a branch and a lateral hole, and 

 shows the porous rod ; text-fig. 9 is taken just below the lateral hole where the main trunk 

 has become tubular again, the porous rod is entirely absent. It will be noticed in text- 

 fig. 8 that there is a similar calcification in the branch, but I am quite unable to find 



* I have changed the feminine termination of ramosa to the neuter ramosum, to agree with the neuter 

 noun. 



