33 



Locality : Laccadive Sea ; 703 fathoms. 



Previously recorded from "Challenger" Stations 194 and 194 A, off Banda ; 

 200 and 360 fathoms. 



Acanella robusta, n. sp. 



This species is represented by a large colony, 250 mm. in height, without any 

 trace of basal attachment. 



The colony is very bushy, the branches being given off from all sides of the 

 stem. They arise from the main stem singly or in twos or fours, and from the 

 primaries the secondaries arise either singly or in twos or threes. Anastomosis of 

 the branches occurs in a few places, but it is by no means common. 



The axis is composed of alternate horny and calcareous joints, the latter 

 marked by longitudinal ridges few in number and often indistinct. 



The polyps are irregularly disposed on the stem, and few in number. On the 

 branches they are placed alternately on opposite sides, but in several cases they 

 arise so nearly at the same level as to seem opposite. 



The polyps are firm and rigid, 3-5 mm. in height, with a basal diameter of 

 about 2 mm. A number of projecting points extend beyond the incurved tentacles. 

 On the polyp body the spicules, some of which are visible to the naked eye, are 

 arranged in two layers, the inner layer consisting of small spicules irregularly 

 disposed, the superficial layer consisting of large spicules with no obvious arrange- 

 ment, some transverse in the lower part, some longitudinal especially on the upper 

 part, but altogether placed so as to form a firm protective and supporting covering 

 to the calyx. In many cases they seem to be more numerous on the abaxial side 

 of the polyp, but in the polyp near the end of a twig they seem to be equally 

 developed on all sides. 



There is a band of longitudinally disposed spicules on the aboral surface of 

 each tentacle, each band consisting of 3-4 rows. On the lateral surfaces small 

 spicules are arranged transversely, and closely packed together so as to form a com- 

 plete coating. 



The ccenenchyma is very thin, with a few small spicules scattered irregularly. 

 Near the base of a polyp the spicules are somewhat larger. 



The polyp spicules are straight or curved spindles, and a few smaller 

 forms which may be called rods. They are all covered by small sharp 

 tubercles. The following measurements were taken of length and breadth in 

 millimetres : 



3-2x0-3; 2-6x0-23; I7x0'l ; O'SxO'l ; 0'2x0'03; O'lxO'017; 0'04x0'01. 



The smallest of these spicules come from the lateral surfaces of the tentacles ; 

 they are flattish, and have prominent tubercles on the edges. 



The spicules of the ccenenchyma are rods, few in number and small in size, 

 0-14x0-025; 0'18x0'025. 

 5 



