REPORT ON THE ALCYONARIA. 59 



pre-opercular series ; of these several in each row })roject with spathuhite free edges. The 

 pre-opercular layer is formed of eight large spicules with deeply hollowed spathulate free 

 edges, which united form a frilled edge around the opercular scales, which latter are 

 eight in number, each deeply folded on itself, the whole not projecting much beyond the 

 limits of the pre-opercular calyx. 



Spicules. — Those of the cojnenchyma measure O-G-0-4 ; 0-5-0'20 ; 0'2- 0'2 mm., of the 

 polyps, 1-1-0-6; 0-7-0-8 mm., and of the operculum 0-9-0-6 ; 07-0"4 mm. 



Habitat. — Station 145a, off Prince Edward Island; depth, 310 fathoms; bottom, 

 volcanic sand. 



5. Stenella acanthina, n. sp. (PI. XIV. fig. 3 ; PI. XX. fig. 10). 



Axis consisting of a main stem, around which numerous branches are arranged in an 

 incomplete spiral. Main axis in one specimen 390 mm. long, the side branches tapering 

 from 50 mm. near the base to about 25 mm. near the summit. The axis is hard, 

 brown in colour, about 4 mm. in diameter at base, consisting of numerous concentric 

 twigs of fibrous substance, with calcareous particles. The nutrient canals form a row of 

 tubes around the outermost layer, over which is a moderately dense ccenenchyma, in 

 which numerous oval disc-like spicules are often very densely packed. 



The polyps are small, in whorls of threes or fours, about 2 mm. in height by r25 mm. 

 at widest diameter. The spicules on the body of the pol5^p vary greatly in size, those on 

 the side nearest the axis being markedly smaller, and enabling the J'olj'p to be folded in on 

 itself ; four series of spicules between the base of the polyp and the pre-opercular layer can 

 be made out. The pre-opercular layer consists of three large acutely spined spicules. 



Spicules. — Those of the ccenenchyma measure 0-302-0-204 ; 0-108-0-104; 0*1- 

 0-1 mm.; those of the polyps, 0-8-0-G ; 0-7-0-5 ; 0-702-0-604 ; the pre-opercular, 

 1-5-0-705; 0-9-0-504; 0706-0-2 ; and those of the operculum, 0-7-0-304 ; 0-4-0-2 ; 

 0-502-0-2 mm. 



Habitat. — Station 320, off' the Rio de la Plata ; depth, GOO fathoms ; bottom, green 

 sand. 



Genus 4. Thouarella, Gray {emend.). 



Thouarella, Gray, Cat. Litliophytes Lrit. Mas., p. 45, 1870. 



Gray's diagnosis of the genus is as follows : — " Coral simple, with long, simple, 

 filiform branches, spreading on all sides of the stem. Bark formed of large imbricate 

 scales. Polype-cells smooth, beU-shaped, scattered on upper side of branches, covered 

 with four or five series of imbricate scales," 



The genus was made for one species, Primnoa OH<a?'c<iccr, Valenciennes. The characters 



