36 



" Scleraxonia with a well-marked axis, which is jointed, i. e., consisting of alternating 

 portions of a hard calcareous and a soft horny substance. The hard joints (internodes) consist 

 of fused calcareous spicules, with but a trace of horny substance : the soft joints (nodes) are 

 formed of loose calcareous spicules in a mesh of horny substance". 



Kükenthal (1908) gives a more extended definition, which may be translated as follows; 



" Scleraxonia with an evident axis sometimes traversed by endodermal canals and consisting 

 of soft (nodes) and hard (internodes) joints. The hard joints consist of complety fused calcareous 

 spicules, and the soft joints consist of rod-like smooth spicules immersed in a horny material. 

 The branching is dichotomous, usually from the nodes, and the colony is usually flabellate. The 

 polyps are borne in calyces arranged either in the lateral borders or one side of the branches. 

 The polyp spicules are spindles or clubs, the cortex spicules are in part " Blattkeulen". 



This definition is acceptable for the purpose of the present work. 



This same writer (Kükenth.\l, 1908) furnishes an excellent key to the genera of the 

 family Melitodidae. This is so well devised that the following translation is offered, the new 

 genus Birottdata being added : 



1. Polyps with exserted calyces. 



A. Branchings from the nodes, only the terminal twigs sometimes from 



the internodes. 



1. Cortex spicules spindles or thorny clubs. 



a. Nodes and internodes traversed by water-vascular canals. 



Polyps ordinarily placed on one side of the branches . . . Melitodes Verrill. 



b. Water-vascular canals not in the internodes. 



Polyps distant and biserially placed Acabaria Gray. 



2. Cortex spicules foliaceous clubs Mopsella Gray. 



3. The foliaceous clubs are nodular in form "Wrightella Gray. 



4. Cortex spicules double wheels Birotulata Nutting. 



B. Branchings from the internodes only Parisis Verrill. 



2. Polyps with inserted calyces (Clathraria) Gray. 



Synoptic view of the genera and species of Melitodid.e 

 collected b)' the Siboga Expedition. 



New genus aod species are indicated by an asterisk (*). 



Melitodes. I Wrightella. 



JM. ochracea. JSl. flabelhini. M. variabilis, ^ir ■ n- . 



\ J '. ' iv . coccmea, II. tongccnsis. 



M. espcri M. ''sqiiauiata^ M. "'inodesta. 



Acabaria. 



A. pJiilippinettsis, A. tenuis, A. '*formosa, 

 A. ^'/licksoni, A. '^triangiilata. 



Mopseida. 



M. clavigeri, M. * s luder i, M. *spongiosa. 



Parisis. 

 P. fruticosa, P. minor. 



*Birotulata. 

 B. '^niinor. 



