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



The coenenchyma and body spicules form a deep layer of long spindles, armed with 

 pointed spines, 0-5 mm. long by 0-03 mm. in diameter, or 0-23 mm. by 0-1-2 mm. 

 There are also broad flat spicules with simple or branched prominences, which often lie 

 in different planes ; and occasionally some spicules similar in appearance to the " Stachel- 

 platten"' met with in Paramuricea. The apices of these often project from the 

 coenenchyma and give it a roughened spiny appearance. These spicules measure 

 0*26 ; 0-35 ; 0-29 mm. ; with a diameter of 0-06 mm. and more. Small, angular 

 spicules with spiny prominences, which are more especially developed from the 

 angles, have a length of O'lG mm. The spicules in the tentacles are arranged in two 

 converging series ; they are simple spiny spindles of from 0"5 to 0'3 mm. in length. 



The axis is horny, flexible, though brittle when dried as in Paramuricea. The 

 colour of the stem is a dark brown, getting lighter towards the termination of the 

 branches. 



The coenenchyma and the polyps are white. 



Habitat. — Station 210, off the Philippine Islands ; depth, 375 fathoms ; bottom, 

 blue mud. 



Genus 5. Cleviatissa,^ n. gen. 



Like Muriceides in its habit, but resembling Paramuricea in its club -like 

 thickened terminal branches, whose apices end in polyps. The spicules of the polyps 

 are spiny, club-like, thickened at one end ; not presenting the regular arrangement 

 of those of Paramuricea. The basal portion of each tentacle, which is not retracted, 

 contains two rows of converging, unilaterally thickened spicules. 



The genus Clematissa shows in its habit a near relationship to Paramuricea. 

 The three species included in it form large colonies branched in one plane, with long 

 terminal branches, which at their apices are thickened and knob -like. 



The coenenchyma is thick, rough, and opaque. The polyps are arranged in short spirals 

 on the stem and its branches ; towards the termination of the branches they are closely 

 crowded, so that they present a knob-hke appearance. The termination of a branch is 

 always formed by a pol5^p. The polyp calyces are bluntly conical, and rise for the most 

 part upright from the stem and its branches. The oesophageal portion of the polyp, 

 which in repose is retracted, is relatively short ; there is always a coUeret of spicules, 

 arranged in a ring-form. 



The tentacular portion, which is not folded inwards, is relatively large and armed 

 with large converging spicules, so that the eight basal portions of the tentacles form 

 over the oral region an eight-rayed conicaUy projecting operculum. 



The spicules of the coenenchyma are stout, usually thickened, with a knob-like 

 termination bearing asperities ; sometimes armed with branched spines, sometimes 



