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



The spicules of the ccenenchyma are again large, and lie very irregularly on the stem 

 and larger branches. In the smaller twigs they lie longitudinally. They are spindle- 

 shaped, often straight, often more or less curved, sometimes thickened at each 

 extremity. They are thickly beset with rough warts, which lie closely together. The 

 largest spicules are 2 - l mm. long and 0'38 mm. broad, but usually they have the 

 following dimensions— 0-97 by 0-154 mm.; 0'89 by 0"15 mm.; 0"84 by 0-126 mm.; 

 0-7 by 0-12 mm. 



Within the ccenenchyma, especially around the principal canals, the spicules have a 

 slender form, and bear only widely separated, delicately pointed, minute spines ; they 

 are chiefly straight, but sometimes curved, more rod-like than spindle-shaped. Their 

 dimensions are 0'434 by 0'042 mm.; 0'75 by 0*09 mm.; &c. 



The colour of the spicules of the ccenenchyma is throughout a beautiful violet-red. The 

 low calyces are formed of circlets of spicules which spring straight from the stem ; the 

 spicules are indistinguishable in form from those of the ccenenchyma, but have a yellow 

 colour, being red only in the older parts of the stem. The collar of the polyps consists of 

 curved spiny spicules. At the base of the tentacles lie curved spicules having one end 

 thickened and covered with the points of sharp spines. They converge in pairs with the 

 points towards the distal end of the tentacle. Their dimensions are 0'336 by - 028 mm. 

 The spicules of the oral region are white, or, in one case, of a dark purplish red. 



Habitat.— Station 177; lat. 16° 45' S., long. 168° 7' E., off Api, New Hebrides; 

 63 to 130 fathoms ; volcanic sand. 



Siphonogorgia xxdlida, n. sp. (PI. II. figs. 2a, 2b; PI. V. fig. 5; PI. VI. fig. 3). 



Of this species onty two fragments have been obtained ; these are, however, sufficiently 

 well marked to form the basis for a new species. The largest piece is a branch giving off 

 at an acute angle near the lower fracture a secondary branch of uniform strength. Numerous 

 remains of twigs show that these arise directly from the main axis, and that they them- 

 selves give off short side-twigs. The main branches and twigs have an irregularly bent 

 course. Apparently the whole colony is stiffly-branched and rigid. The main branches are 

 very slightly flattened in one plane, the twigs rising chiefly from two sides. The largest 

 branch is 6 mm. thick at its lower end, and 4 mm. thick where it is broken at its further 

 extremity, a distance of 100 mm. A secondary branch is 5 mm., the twigs 3 mm. in 

 thickness at the base. The polyps are borne only upon the twigs and sub-twigs. They 

 are small, arranged in a spiral, having conical calyces, which, towards the lower portion, 

 are somewhat laterally compressed. The oral region of the polyps is highly retractile. 

 Three or four closely clustered calyces form the apex of the twig, and give to it an 

 apparently thickened end. 



In a transverse section of a twig may be seen the four central stem canals, which are 



