438 Messrs. J. Wood-Mason and A. Alcock on 



A magnificent specimen, with a major diameter of nearly 

 8 inches, from Station 117, 1748 fallioms. 

 Colour in the fresh state plum-purple. 



Family Echinasteridse. 



DiCTYASTER, gen, nov. 



Disk large, and flat like the short rays. 



Abactinal surface covered with tough membrane, beneath 

 which are narrow plates bearing stout spinelets, and forming 

 a wide-meshed irregular network, the meshes of which are 

 occupied by large groups of papulre. 



Marginal plates, especially the supero-marginals, small and 

 inconspicuous, the infero-marginals each with a short comb of 

 stout spines ; the intervals between the plates with groups of 

 papulaj. 



Actinal interradial areas large, covered with a smooth thick 

 membrane, beneath which is a reticulum of irregular plates. 



Adambulacral armature forming a double palisade along 

 the furrow. Tube-feet in a double row, their ti})s ending in 

 a sucker. 



Madreporiform body small. Anal aperture subcentral. 

 No pedicellariffi. 



19. Dictyaster xenophiluSj sp. n. 



Plectaster, sp., Wood-Mason and Alcock, Ann. & Mag. Nat. Hist. 

 Jan. 1891, p. 14. 



Rays 5. l{ = 2-5r. 



The whole animal invested in a thick coriaceous mem- 

 brane. 



Disk and rays flat and broad ; interbrachial arcs wide. 



Abactinal surface with narrow plates, bearing large coarse 

 spines solitary or in rows of two or three, and forming a wide- 

 meshed reticulum, the meshes of which are occupied by 

 papulee in large crowded groups. 



Infero-marginal plates alone at all distinct, not in contact 

 one with another ; each bears a hinged comb of from three to 

 five large coarse spines along its actinal margin. 



Adambulacral plates covered by the general thick coria- 

 ceous investment ; the narrow ambulacral groove is bounded 

 on each side by a double series of stout palisade-like spines, 

 those in the outer series being about half as numerous but 

 about twice as big as those in the inner scries. Mouth-plates 

 hardly differentiated. 



