60 PROF. F. J. BELL ON NEW [Feb. 20, 



to a third of the length of the body, much contracted at its free 

 end. 



The interradial pieces of the calcareous ring are not as much as 

 half the width of the radial, nor are they quite so high. Both sets 

 are elongated, their sides parallel, and without any prominent notch 

 at their proximal end. 



The only spicules appear to be the very sparsely distributed rods 

 found in the walls of the suckers. I may point out that in another 

 species of this genus lately examined by me I have noted a complete 

 absence of calcareous spicules. 



Length' 11 ; 52 millini. Greatest breadth 38 ; 25. 



In the larger specimen the Polian vesicle is 25 niillim. long, and 

 the distance between the points of origin and insertion of the re- 

 tractors is 45 millim. 



Colour dark or lighter brown, anterior end white in parts. 



Possession Bay, Straits of Magellan. Coll. Cunningham. 



Thyone cunninghami. (Plate XV. fig. 4.) 



Body stout, narrowing suddenly at the hinder end ; tentacles 

 subcqual, yellowish cream-coloured ; suckers much better developed 

 on the trivial than on the bivial surface. Skin thicker posteriorly 

 than anteriorly ; quite thin in front. Anus without teeth, but 

 fringed by papillae. 



Retractors stout, distinctly double, inserted very far back, behind 

 the middle of the length of the body. Polian vesicle delicate, elon- 

 gated in form and not very short. The distal end of the buccal 

 skeleton is very stout ; the interradial is a little narrower than the 

 radial piece, or, as the sides of both are not exactly parallel, they 

 are rather narrower at their free end than at their base. 



Spicules rather delicate rods, often pitchfork-shaped, or swollen 

 and perforated at their ends, sometimes more irregular in form. 



The single specimen is 50 millim. long, 17 wide; Polian vesicle 

 10 long; insertion of retractors 28 millim. from their origin. 



Colour light grey. 



Off Dungeness, Patagonia. Coll. Cunningham. 



Phyllophorus dobsoni. (Plate XV. figs. 5, 5 a, 5 &.) 



Of the four species^ of this genus already known, it would be with 

 one only, P. holothuroides of Ludwig, that, even at first sight, we 

 should feel inclined to associate this new form. The spicules, the 

 buccal armature, and the arrangement of suckers on the trivium are, 

 however, very different. 



Rounded in form, about twice as long as broad, with a soft in- 

 tegument, with the suckers irregularly distributed, covering the 

 bivium and both ends, but scarce or absent in the central portion of 

 the trivium. The retracted gills appear to be 18 in number, of 



* Owiijg to the shape of the bodies their length can only be approximately 

 given. 



2 The name only of P. tenuis can be said to be known. 



