OF THE HERGUI ARCHIPELAGO. 



233 



colour of the zooids appears to reside wholly in the soft parts 

 (the tentacles?), which appear dark brown to black under the 

 microscope. 



This form appears markedly distinct from all species of which 

 satisfactory information can be obtaiued ; but in its colour 

 S. capitata of Verrill possibly resembles it ; this is described 

 (Bull. Mus. Comp. Zool. Harvard, i. p. 40) as yellowish grey, aod 

 the spicules as white, not very conspicuous, the large ones not 

 very numerous. From its neighbours, S. aurora and boletiformis, 

 it is well separated by its colour, by the transverse wrinkling 

 of the axis and upper part of the stem, and (connected with 

 this last point) the horizontal position of some large spicules 

 in the cortex of the axis; the much branched condition of the 

 proper spicules of the stem is another point distinguishing it 

 from these two species. 



Family Gorgoniid.e. 



Plexaura iisdica, n. sp. (Plate XVIII. figs. 1-5.) 



*Kamose, flabellate, with decided tendency to unilateral pin- 

 nation ; after the first one or two divisions the branches assume a 

 suberect position f ; origins of lower branches about | to 1 inch 

 apart, those of upper ones very distant ; terminal pinnae very 

 long (may attain a length of 6 inches), bluntly rounded or slightly 

 clavate. Lower branches subcylindrical or flattened, flattening 

 especially marked just below origin of branches ; terminal pinnae 

 cylindrical, commonly somewhat clavate. Base spreading widely. 

 Cortex in dry state about 3 to "5 millim. thick near base, about 

 *6 millim. thick near periphery of colony; colour strong scarlet. 

 Verrucae small, depressed below the general level of the cortex, 

 oval in outline, with the long diameter parallel to that of the 

 branches, and about 5 millim. in this dimension ; thickly distri- 

 buted over every part of the branches, viz. about 5 to 1*0 millim. 

 apart. 



Axis of stem subcylindrical, with distinct though irregular (in 

 the single dry specimen) longitudinal grooves, black; that of 



* Description taken, except where otherwise stated, from the large dry 

 specimen. 



t In both the specimens, one or more of the lower branches are given off 

 almost horizontally, and their pinna? originate almost at right angles from their 

 upper sides. 



