228 



THE VOYAGE OF H.M.S. CHALLENGER. 



distributed, larger and smaller, short, stout, erect branches. These break up, either 

 directly or at the end of other ramifications, into a number (three to six) of short twigs, 

 which are thickly covered with polyps arranged in quincunces. The bodies of the polyp.s 

 curve inwards in death, and cover each other like tiles. These terminal branches thus 

 form polyp-bearing heads or short, conical clusters, of which those belonging to one branch 

 stand close together. The main stem behaves at the end like the branches and secondary 

 branches. 



Height of the colony, .... 

 Diameter of the base, .... 

 Diameter of the main stem before the branches come off. 

 Length of one of the larger branches. 

 Diameter of the .same, .... 

 Length of a cluster, .... 



Diameter at the base of a cluster, 



65 mm. 

 25 

 18 

 24 

 12-14 



6 



4 



The habit of the colony is completely that of Nephthya chahrolii, Aud., with which it 

 might be easily confounded on a superficial examination. The greater toughness of the stem 

 and branches, which have a much firmer consistence internally, arid the homogeneous 

 character of the outer covering in the stem and polyps, enable one, however, to recognise 

 a distinction even with the unassisted eye. The closely crowded, club-shaped polyps, 

 which are curved inwards towards the axis of the clusters, show at the end eight folds, 

 the expression of the folded tentacles. They measure up to 2 mm. in length and 1 mm. 

 in diameter at the tentacular portion. Young polyps arise between the old ones over 

 the whole cluster. The canals in the smaller branches are narrow and very numerous ; 

 in the axis of one cluster there are forty to fifty, having a diameter of 0'3 to 0"5 mm. 

 The thickness of the dividing walls reaches 0"1 mm. In the main stem the canals may 

 be counted by hundreds, with a maximum diameter of 0-5 mm. The .spicules are small, 

 closely placed, foliaceous and spiny clubs. The broader portion of the spicule, which in 

 the polyps projects above the surface, consists of a foliaceous expansion, flattened in one 

 plane. This is supported by three stout divergent ribs, which project marginally like 

 spines. There often comes off" from the middle of the foliaceous expansion, in a vertical 

 plane, a lateral expansion. The base exhibits three divergent, often branched, root-like 

 processes. 



The height and breadth of these sjJicules, measuring by breadth the transverse 

 diameter of the foliaceous expansion, are as follows: — 0-06 by 0"09 ; 0'08 by O'OGS ; 

 0-^ by 0-09 ; 0-06 by O'l mm. 



The colour of the colony in alcohol is yellowish- white. 



Habitat. — Samboaugan ; beach. 



