ALCYONARIA — J. A. THOMSON AND DORIS L, MACKINNON. 679 



of the stem is missing. The stem has a maximum diameter of 4 

 mm. ; the average diameter of the larger branches is 2 mm., and 

 of the twigs, 1 mm. Another specimen, also incomplete, has a 

 height of 16 cm,, with a span of 11 cm. The lower part of the 

 stem is overgrown by a sponge. 



Polyps occur here and there on the branches, but they are 

 mainly confined to the twigs, along each side of which they are 

 arranged alternately in a single row. Frequently this arrange- 

 ment becomes ii'regular, the polyps encroach on the middle line, 

 or a double row may be formed along each side. There are 

 about fifteen polyps to 1 cm. in each row. 



The polyps are small, -S-'TS mm. in height, club-shaped, trun- 

 cate, and turned upwards towards the tip of the twig. They 

 are covered with closely-fitting, elongated spicules arranged 

 transversely, which either interlock by means of their dentate 

 margins, or overlap one another ; the abaxial rows are composed 

 of about sixteen such spicules arranged in an imbricate manner. 

 Similar spicules form a low, eight-rayed operculum. The spicules 

 of the ccenenchyma are like those of the polyps, but follow the 

 longitudinal direction of the stalk and form a sort of pavement 

 over its surface, adjacent spicules being closely interlocked by 

 their teeth. The calcareous internodes of the axis bear fine 

 longitudinal ridges, which are dentate at the upper and lower 

 ends of the joint. The spicules are small, colourless, somewhat 

 flattened spindles and lancet-shaped plates, frequently curved, 

 and bearing numerous sharp, tooth-like warts, which are usually 

 more strongly developed on one side of the spicule than the other. 

 The following measurements were taken of length and breadth 

 in millimetres :— -238 x -085 ; -17 x -OfiS ; -1 36 x -05 1 . 



There are also numerous smaller spindles and forms approach- 

 ing clubs:— -153 x -025 ; -112 x -035 ; -085 x -034 ; 068 x -017 

 mm. 



The colour of the colonies is pale-brown to cream-white, the 

 axis occasionally tinged with pink. 



Locality. — Eleven miles east of Broken Bay. 



Genus ACANTHOISIS, Wright and Studer. 



AOANTHOISIS FLABELLUM, Wright and Studer. 



(Plate Ixii., figs. 1 and 2.) 



Acanthoisis fiabellum, Wright and Studer, Chall. Rep., Zool.,xxxi., 

 1889, pp. 45-46, pi. viii., figs. 1, la., lb., pi. ix,, fig. 12. 



Stations 22, 47 and 53. 



Some very fine fan-shaped specimens of an orange-brown 

 colour agree with Wright and Studer's description of Acanthoitis 



