Indian Deep-sea Asteroidea. 113 



fathoms, on bottoms of green mud or of coral and Globige- 

 >•^*/^a-ooze, only differing from the described type, which was 

 dredged by the ' Challenger ' in the Indian Ocean off the 

 Crozet Islands, in having the disk relatively smaller. In 

 one specimen the rays are most remarkably inflated m their 

 basal fourth. 



DiCTYASTER, Alcock and Wood-Mason. 

 Rays 5. 



Disk large, quite flat actinally, but slightly inflated abac- 

 tinally, as are the broad rays ; both disk and rays are invested 

 tliroughout by a thick, smooth, coriaceous membrane, beneath 

 which is a reticulum of plates. 



Abactinal surface with coarse irregular plates, some or all 

 of which bear coarse spinelets, and forming an irregular wide- 

 meshed network, the meshes being occupied by large groups 

 of papulae. 



Supero-marginal plates absent or inconspicuous ; infero- 

 marginals conspicuous and bearing one or more stout spines ; 

 the group of papulse extend downwards as far as the infero- 

 marginal plates. 



Actinal interradial areas large, the smooth intermediate 

 plates extending to the tip of the rays. 



Adambulacral armature in the form of a double furrow- 

 palisade. 



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



Madreporiform plate small, single. Anus subcentral. No 

 pedicellaria^. 



This genus appears to be nearest related to Plectaster ; it 

 is instituted for the reception of two Andaman forms, Dicty- 

 aster xenopliilus^ from deep water, and Dictyaster Wood- 

 Masont, a littoral form recently discovered in Prof. Wood- 

 Mason's rich Andaman collection. 



48. Dictyaster xenophilus, Alcock and Wood-Mason. 

 (PI. V. figs. 8, 9.) 

 Dictyaster xenophilus, Ann. & Mag. Nat. Hist., Dec. 1891, p. 438. 

 Rays 5. R = 2-5 r. 



Disk large and, like the short broad rays, flat actinally, 

 and often a little inflated abactinally ; both disk and rays are 

 everywhere invested in a thick leathery membrane which 

 covers all the plates and their spines — abactinal, actinal, and 

 adambulacral. 



