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



twigs lie all in one plane. The coenenchyma on the stem and larger branches is thick, 

 on the twigs thin and transparent. The polyps are large, cylindrical, and up to 4 mm. 

 in length. They have a broad base and are placed obhquely to the stem. They are 

 numerous on the stem and on the main branches, so far as one can tell in the uninjured 

 places, there are as many as four in a spiral in one internode ; on the thinner twigs there 

 are two, laterally placed, in an internode, on the terminal twigs three or four. In 

 addition to the polyps there are, in the coenenchjina of the larger branches and of the 

 stem, zooids without tentacles. These form conical structures which project 0'5 mm. 

 above the coenenchyma. They are placed abundantly between the poly^js, and are 

 recognisable with the unassisted eye as little warts. 



The axis is hard, horny, in the stem and in the thicker twigs inflexible and brittle, in 

 the finer ramifications flexible and elastic. Its surface is shining, with very intense metallic 

 reflections. The spicules of the coenenchyma are lancet-shaped, flat, somewhat iridescent 

 bodies, which lie close together and partially overlap one another on opposite sides ; they 

 are continued into the zooids, in which they are longitudinally placed. In the polyps 

 the spicules are transversely placed, overlapping, broad oval to lancet-shaped scales, 

 which are finely toothed at the edges ; in the tentacles there are longitudinally placed, 

 broad spicules, with truncated ends, sometimes forked on one side. 



This form would show a very diQ"erent ramification from the other species of the 

 genus, if we had before us, in the existing fragment, devoid of the lower end, a complete 

 colony. But the whole mode of ramification agrees so completely with that of a single 

 branch of the species hitherto considered, that we may pretty safely assume that we are 

 here only dealing with the torn-oS" branch of a really gigantic colony. 



The main stem has at its lower end a diameter of 5 mm., it gives off" immediately, on 



one side, a branch of 3 mm. diameter, and 9 mm. higher up a branch of 3 "5 mm. diameter ; 



at these points it undergoes an angular bending towards the opposite side, and then, after 



giving off" another thick branch, 4 mm. in diameter, at a distance of 45 mm. higher up, 



in the direction of the former, it is produced into a taU portion bent in a zigzag manner. 



The height of the portion which may be regarded as the main stem reaches 300 mm. 



At each angle which the stem forms thinner branches arise, which again bear twigs, and 



the three stout branches behave in the same way ; the last fine twigs of the latter belong 



to the fifth and sixth order. Each of the larger branches, like the main stem, gives off", 



in addition to three or four twigs which have the same thickness as their main stem, 



numerous smaller twigs, which undergo further ramification only to a slight extent. 



Branches and twigs come oft' at acute angles ; their internodes are large, in the larger 



twigs 9 to 10 mm. long. The entire ramification takes place in one plane. The colony 



may be characterised as branched in a one-sided, fan-hke manner. 



The coenenchyma on the thicker branches is thick and easilj' stripped off" ; on the 

 thinner twigs it is transparent. The polyps stand upright on the stem and thicker 



o 



