114 Mr. A. Alcock on 



The narrow poliont abactinal plates form a very wlde- 

 mcslied network, the sunken meslies of whicli are oceiipled by 

 large grouped masses of papulae ; all the plates carry coarse 

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



The supero-marginal plates hardly differ from the ordinary 

 abactinal plates in form and armature, but they constitute a 

 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 lamince, 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 scries of plates is occupied by papulae in 

 large isolated groups. 



Adambulacral plates small, each with two, but near the 

 aetinostome 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 trilobcd ; 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 those 

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

 from four to six ligulate spines, increasing in size from t!ie 

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

 ligulate sjiines, placed transversely. 



Actinj'.l 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. 



^ladrc] oriform 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 Chcetopod is often found on the actinal inter- 

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



Andaman frlea, 1 70 to 29U fathoms. 



Family Pedicellasteridae. 



Pedicellaster, Sars. 



49. Pedicellaster atndus, sp. n. 



Kays 5. 1\ = 11 r. R = about 100 millim. in 

 tlic type specimen. 



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



