172 DR. J. PEARSON ON MARINE FAUNA [Feb. 1, 



in the specimens under examination. In the ' Challenger ' 

 specimen the papillae were very obvious. 



There are nine arborescent tentacles in the larger specimen and 

 ten in the other specimen. All the tentacles are about the same 

 size. 



There are five ill-defined calcareous teeth around the anus. 

 The calcareous ring has no posterior prolongations. There is one 

 large Polian vesicle — 28 mm. long — and one stone-canal. There 

 are five well-developed retractor muscles extending from the 

 calcareous ring to the body-wall. They are attached to the latter 

 a,bout half-way down the body. The respiratory trees are well 

 developed. The alimentary canal is large and the reproductive 

 organs are very large and consist of two bundles. 



Theel gives drawings of the whole animal, of the spicules and 

 the calcareous ring. 



The spicules are few in number and agree with Theel's figures. 

 Length of buttons 63 yu ; breadth 55 fx. 



As Theel and Koehler have pointed out, this species differs in 

 a marked manner from the other species of the genus Colochirus. 



After a careful examination I have decided to establish a new 

 genus for this form. Undoubtedly it does not possess any of the 

 outstanding features of the genus Colochirus. The body is not 

 quadrangular ; the anterior and posterior ends of the body are 

 not pentagonal ; the mouth is not surrounded by five valves ; and 

 the two ventral tentacles are not smaller than the rest. The 

 deposits are few in number and unlike those of Colochirus. 



It agrees with Colochirus (1) in having three rows of pedicels 

 on the trivium and only papillse on the bivium, (2) in being 

 a Dendrochirote having a calcareous ring without posterior 

 prolongation. 



General distribution. ' Challenger ' St. 203, 1 1° 6' N., 123° 9' E. 

 Indian Ocean. 



The characters of the new genus may be summarised as 

 follows : — 



Pseudocolochirus, gen. n. 



Body cucumiform. Pedicels present only on the trivium where 

 they are arranged in three well defined rows. Small papilla? 

 scattered on the bivium. A few also on the trivium. Ten ar- 

 borescent tentacles of equal size. The anus is surrounded by five 

 calcareous teeth. The perisome is thick but is not strengthened 

 by many deposits. The spicules are few in number and consist of 

 small perforated buttons. The calcareousring is devoid of posterior 

 prolongations and has five well developed retractor muscles. 



Stichopus chloronotus Brandt. 



Stichopus chloronottts (subgenus Perideris), Brandt, 1835 (6). • 



Stichopus chloronotus Selenka, 1867 (10). 



Stichopus cyl'mdricus Haacke, 1880 (14). 



Sliehojms chloronotus Ludwig, 1882(15); Lampert, 1885 (1 



