76 



Acamptogorgia circium, u. sp. Plate V. fig. 3 ; Plate IX. fig. 1. 



Two specimens, 16 cms. and 20 cms. in length. There are flat, spreading 

 basal attachments. The branching is very irregular. In one specimen the prin- 

 cipal branches are confined to one plane, and the secondary branches are either 

 in that plane, or arise at right angles to it. Of the secondary branches, those 

 that arise on the track of the principal branches curl round, and come to lie 

 either in the plane of the primary branches, or again at an angle to it. so that 

 the branches on a whole are arranged in three directions. There is also abundant 

 anastomosis. In the other specimen the branching is even more irregular, the 

 secondary branches coming off from three sides ; but there is no trace of 

 anastomosis. 



The horny axis is yellow in colour, darker in the older parts and lighter in 

 the younger parts, and as far as examined shows no trace of lime. The core is 

 divided into a series of chambers by vertical partitions, a structure usually well 

 seen in this genus. The surface of the axis in the main stem and branches is 

 marked by a large number of spirally arranged ridges ; in the secondary branches 

 the ridges run longitudinally. 



The verrucse are prominent, arising irregularly from all sides of the stem and 

 branches, and each is surrounded by a crown of spines. They reach a height of 

 3 mm., and have a basal diameter of about 2 mm. 



In the polyp the spicules are arranged in a ring of four rows round the base 

 of the operculum, and the spicules in the high conical operculum are placed en 

 chevron with two spicules in each point. 



The surface of the verrucee and general coenenchyma bristles w r ith projecting 

 spines, so that the whole colony has a very rough thorny appearance, which 

 suggested the specific name circium. 



The spicules of the polyps are spindles and clubs with divaricate folia, covered 

 by spines which either stand perpendicularly, or are inclined to the surface of 

 the spicule. The following measurements were taken of length and breadth in 

 millimetres : 



1. Spindles straight or curved, 1 -3x0-15; 0'9x0'075; 0'2x0'025. 



2. Clubs with folia, O'9-l in length by 0'4-07 across the folia. 



Many of the spindles have one end with spines arising perpendicularly to 

 the surface, and the other end with slanting spines, especially in the curved forms. 

 In the clubs, the length of the spine varies from 0'3-0'6 mm. 



The spicules of the general cceneiichyma are (1) spindles straight or curved ; 

 (2) curved spindles with a foliaceous expansion about the middle of the convex 

 side ; (3) U-shaped spicules, and very irregular forms. The following dimensions 

 were noted : 



Spindles from O'.VO'G mm. in length, and from 0'02-0'05 in breadth. 



