398 



THE VOYAGE OF H.M.S CHALLENGER. 



2. Papular areas confluent laterally. Madre- 

 poriform body large and compound . 

 ii. Abactinal and marginal plates (in fact the whole test) 

 covered with a thick membranous investment 

 fi. Abactinal plates not forming regular longitudinal series. 

 i. Adambulacral armature granuliform, two or three 

 series. No papulae on the actinal surface. Abac- 

 tinal plates comparatively small. 



1. Rays more or less cylindrical. Papulae in 



areas irregularly distributed amongst the 

 abactinal plates . 



2. Rays trigonal. Papulae in one or two con- 



tinuous uninterrupted rows on each side 

 of the ray ...... 



ii. Adambulacral armature papilliform or spiniform, 



subprismatic, usually in three series. Abactinal 



plates comparatively large. 



1. 



the actinal 



Rays rounded. Papula? on 



surface. Papula? in areas 



2. Body pyramidal, rays triangular in section. 



No papulae on the actinal surface. Papulae 



single, isolated ..... 



b. Abactinal and marginal plates covered with membrane, the former and 



occasionally the latter bearing isolated skin-covered spinelets . 



a. A single genus ......... 



Pharia. 



Leiaster. 



Linckia. 



Pltataria. 



Nardoa. 



Nareissia. 



Metrodirin*. 



Metrodira. 



Subfamily Ch^etasterin^;, Sladen, 1888. 

 Genus Chsetaster, Midler and Troschel. 



Chstaster, Muller and Troschel, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, April 1840, p. 103. 

 1 Astropus (subgen.), Gray, Ann. and Mag. Nat. Hist., Nov. 1840, vol. vi. p. 182. 

 Nepanthia (pars), Gray, Ann. and Mag. Nat. Hist., Dec. 1840, vol. vi. p. 287. 



This singular genus was originally ranked with the Astropectinidse, but was removed 

 by Viguier 1 in 1878 to the Linckiidse. The justice of this step has recently been recog- 

 nised by Perrier. 2 I fully concur in this, although I regard Clisetaster as a very abnormal 

 member of the family, and have placed it in a distinct subfamily. 



Chorology of the Genus Chsetaster. 



a. Geographical distribution : — 



Atlantic : Two species between the parallels of 10° and 40° N. 



Chsetaster longipes, from the Mediterranean, and off the Azores 

 and Bermuda. Clisetaster nodosus, from Guadeloupe. 



1 Archives de Zool. exp'er., 1878, t. vii. p. 147. ' 



* Nouc. Archives Mux. Hist. Nat., 2e Seri6, 1884, t. vi. p. 1G4. 



