108 THE VOYAGE OF H.M.S. CHALLENGEE. 



coenenchyma and the polyps in spirit specimens are brownish -grey, but white when 

 dried. 



Habitat. — Station 135, Tristan da Cimha ; depth, 360 fathoms; bottom, volcanic 

 sand. 



2. Clematissa rohusta, n. sp. (PL XXII. fig. 9 ; PI. XXVI. fig. 5). 



The stem is upright, loosely branched in one plane. The principal stem gives off 

 branches at right angles, in alternating series on either side, and at long intervals. 

 These branches stand off horizontally from the stem. The branches sometimes equal 

 the stem in thickness, and sometimes surpass it in length. These give off single, 

 perpendicular, lateral twigs which now and then anastomose with other branches ; they 

 sometimes, but rarely, give off secondary twigs. The unbranched terminal portions of 

 the branches are long, tencbil-like, and with thick knob-like endings ; the length of the 

 principal stem is 250 mm., with a diameter at its base of 7 mm. 



The branches extend to a length of 240 mm. and over, with a basal diameter of 

 3 mm. The unbranched terminal portions of the branches reach to a length of 

 100 mm. 



The polyps are spirally arranged on the stem and branches, at intervals of from 1 

 to 2 mm. ; at the termination of the branches only are they closely packed. The 

 polyps are about 1*5 mm. in height, with the same measurement for their basal 

 diameter; the tentacular operculum is I'S mm. high. 



The spicules in the coenenchyma and in the polyps are large, club-shaped, armed 

 with branched spines, and often curved and bent ; the club-shaped warty extremities 

 project and give the polyps a rough warty appearance. These measure 0'5-0"12 ; 

 0-52-0-08 ; 0-62-0-1 ; 0-42-0-1 ; 0-54-0-067 ; 0-62-0-08 mm. In a deeper layer 

 they are more spindle-shaped, and are packed close together, with their spines inter- 

 locking ; these measure 0-6-0 -07 ; 0'38-0-05 ; 0-3-0-04 ; 0-38-0-07 mm. The spicules 

 of the tentacles are feebly bent spiny spindles. 



The axis is horny, fibrous, soft, and very flexible, so non-elastic that the branches 

 out of water droop loosely. 



The stem is of a yeUowish-brown colour. The coenenchyma and polyps in spirits 

 are of a brownish-yellow, but when dried are yeUow. 



Habitat. — Station 310, Sarmiento Channel, Patagonia ; depth, 400 fathoms ; bottom, 

 blue mud. 



3. Clematissa obtusa, n. sp. (PI. XXIII. fig. 2 ; PI. XXVI. fig. 4). 



The stem is feebly branched in one plane. The principal stem gives off, on one side 

 only, two branches, which are either unbranched or very feebly so ; the terminal twigs 



