114 Mr. A. Alcock on 



The narrow salient abactinal plates form a very wide- 

 meslied network, the sunken meshes of which are occupied by 

 large grouped masses of papulae ; all the plates carry coarse 

 spines, either solitary or in rows of two or three. 



The su])ero-marginal plates hardly differ from the ordinary 

 abactinal plates in form and armature, but they constitute g, 

 fairly well-defined border to the rays. 



The infero-marginals are separated from one another by an 

 interval equal in length to the plates themselves ; they are 

 distinct laminae, with their surface horizontal and with a 

 sharp edge that projects laterally and bears a horizontal comb 

 of three to five (usually three) coarse spines. The space 

 between the two series of plates is occupied by papulas in 

 large isolated groups. 



Adambulacral plates small, each with two, but near the 

 actinostome often three, narrow ligulate spines along and 

 almost within the furrow, and on the margin of the furrow 

 with one much larger broadly ligulate spine, the truncated 

 end of which is usually bilobed or trilobed ; so that the 

 narrow ambulacral groove is bounded on each side by a 

 double palisade of ligulate spines, those of the outer series 

 being about half as numerous but about twice as big as tliose 

 of the inner series. Mouth-plates with a furrow-series of 

 from four to six ligulate spines, increasing in size from the 

 periphery to the centre, and actinally with two of the broadly 

 ligulate spines, placed transversely. 



Actinal interradial areas large ; the plates, which are quite 

 smooth and which are separated from one another by 

 intervals equal in breadth to the plates themselves, extend 

 nearly to the tip of the ray. 



Madreporiform plate situated almost in an interbrachial arc, 

 very finely and closely striated. Anus subcentral, surrounded 

 by blunt spinelets. 



Tube-feet in a double row, ending in a sucker. 



Colour in the fresh state chestnut-brown. 



A symbiotic Chgetopod is often found on the actinal inter- 

 radial areas, on which also it often lays its eggs. 



Andaman Sea, 170 to 290 fathoms. 



Family Pedicellasteridse. 



Pedicellastee, Sars. 



49. PediceUastcr atraius, sp. n. 



Rays 5. E = ll r. E- = about 100 raillim. in 

 the type specimen. 



Disk extremely small, circular (button-like), abactinally 



