REPORT ON THE ALC YON ARIA. 19 



coenencliyma are smaller. The axis is brittle, inflexible, yellowish-brown, smooth on the 

 surface, brightly iridescent. . 



This species, represented by a colony broken into several pieces and wanting the 

 base, is distinguished from those most nearly related to it by the copious branching, 

 which takes place in diff"erent planes, so that the colony acquires a bushy appearance ; 

 by the development of numerous polyps on the stem, which have a somewhat different 

 structure from those of the branches, and by the little zooids, which protrude from the 

 coenenchyma and give to it a roughened appearance. 



The main stem rises in an erect manner, its length reaching 200 mm., and in the lower 

 part it is 2 mm. in diameter. At short intervals it gives off branches at right angles, 

 which are I'd mm. distant from one another. These form regular spirals around the 

 stem, so that the fifth Ijranch then comes to be in line with the first again. The little 

 angular bendings which the stem undergoes at the point where each branch comes off', 

 give to its axis a spiral appearance. The ramification of the branches takes place 

 according to the usual rule. The main branch, which in the upper third of the stem 

 reaches 30 mm. in length, is angularly bent in diff"erent planes, but usually horizontally 

 to the stem, and gives off twigs of a like nature, from which arise twigs up to the fifth 

 order. All stand at angles of 40° to 45° to one another. The internodes are, on an 

 average, 4 mm. long. 



On the stem are placed polyps, with very short calices and wide oral discs from 

 which the eight tentacles arise, they are placed in spirals around the stem, and there are 

 always two between each pair of branches. The tentacles are expanded in all, and the 

 power of contraction appears to be less in the axial polyps than in those of the branches. 

 On the branches and twigs there is one polyp on each intemode, on the thicker 

 Ijranches this is perpendicular to the base, on the terminal twigs it is directed obliquely 

 outwards. Its base is expanded, the body being constricted in front of the calyx opening. 

 The length reaches 2 mm. 



The zooids are conical-shaped bodies of 0'12 to 0"15 mm. in length, 0'05 mm. in 

 diameter, which are abundantly scattered in the coenenchyma of the stem and branches, 

 and cause the surface of the latter to appear as though roughened. Every zooid exhibits 

 an ectodermal covering, which is considerably thickened on the summit of the conical 

 body, and contains a number of thread-cells ; at one side, between the base and the apex, 

 is the mouth-opening, which in the different zooids appears sometimes circular, some- 

 times a mere slit, which seems to indicate the existence of a considerable extensibility of 

 the opening. 



No oesophageal tube can be recognised, and the digestive cavity passes directly into a 

 longitudinal canal of the coenenchyma. 



The axis in the stem is hard and brittle, yellowish, with shining surface, which is 

 strongly iridescent. In the branches the axis becomes more flexible and elastic. 



