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



position, at any rate show that it cannot belong to the genus Hyalopathes as defined by 

 Milne-Edwards. The axis is not smooth, neither is it seini-hyaline. With regard to 

 the glassy appearance of the black sclerenchyma, it may be stated that this is a character 

 of frequent occurrence amongst the Antipathidse, and one which has no generic value. 

 The same appearance was noted by Marsigli in his description of the species which we 

 now know as Antipathes dichotoma, Pallas. I have also observed it in several species of 

 Cirrhipathes and other forms, and, so far as could be ascertained, this aspect is not 

 constant in all the specimens of a species, but appears to depend to some extent on age. 

 So far as can be ascertained from Haeckel's figure and description, this species differs 

 from any other with which I am acquainted in the arrangement of the zooids on the 

 corallum. In other branched forms the zooids are almost invariably arranged in a 

 single linear series on the branches and branchlets. In Haeckel's figure the corallum is 

 represented as very thick in proportion to its length, and the branches do not appear to 

 taper much. The zooids are relatively small, radiate in outline, and not confined to one 

 aspect of a branch. They are a considerable distance apart, and apparently distributed 

 irregularly at any point around the axis. The thickness of the corallum and the shape 

 and arrangement of the zooids recall the characters of the genus Cirripathes as modified 

 in the present Report, but the corallum in this species is branched. On account of the 

 fact that we are stUl ignorant of the structure of the zooids and the arrangement of the 

 spines, I have temporardy included this species amongst a group of others which are too 

 imperfectly known at present to have a definite position assigned to them. 



In accordance with this arrangement I propose to drop the generic name Hyalopathes, 

 which should be regarded as a synonym of Iridogorgia, Verrill. Of the three species 

 comprised in it, the type species is not an Antipatharian ; another which does not 

 possess the generic characters is probably closely allied to Cirrhipathes, whilst we 

 know too little of the third to assign it any definite position. 



The remaining species of the old genus Antipathes, Pallas, are divided by Mdne- 

 Edwards into three genera, the characters of which depend solely on the mode of 

 branching, and the presence or absence of fusions between adjoining parts of the 

 corallum. He retains the name Antipathes for those forms which appear to be without 

 fusions, and divides those in which fusions are frequent into two sections. The name 

 Arachnopathes is suggested for those in which the corallum forms a more or less thick 

 confused mass, the branchlets of which are distributed all around the branches, that of 

 Rhipidipathes for the flattened fan-like forms, in which the extension of the colony 

 takes place chiefly in one plane. 



It has been admitted on all sides that genera of Antipatharia based solely on skeletal 

 structures must be more or less artificial, and Milne-Edwards himself anticipated that 

 further researches would necessitate a modification in his arrangement. Unfortunately 

 we do not yet possess all the information necessary for a proper elucidation of the 



