98 Mr. A. Alcock on 



Madreporiform plate completely hidden. Anus central. 

 Colour in the fresh state pale yellowish pink. 

 Bay of Bengal, 1748 fathoms, Glohiyerina-oozo. and 

 pumice. 



32. ParacjonasteVj sp. 



Parayonmter, sp., Ann. & Mag. Nat. Hist., Dec. 1891, p. 430. 



A s]iecimen too much mutilated for description was taken 

 with the above; it is characterized by having the pa))ula^ in 

 distinctly circumscribed papularia, over which the paxillre are 

 singularly large and prominent. 



Mediastek, Stimp.son. 



33. Mediaster i-oseus, sp. n. 

 Mediaster, sp., Ann. & Mag. Nat. Hist., Jan. 1891, p. 13. 



E-ays 5. R = 4 r. R, = 42 raillim. in the 

 type specimen. 



Disk small, flat ; rays flat, tapering, rigid. 



Abactinal surface of the disk covered with paxilliforni 

 plates which in the centre and interradii are small, irregular 

 in shapCj and crowded together, but which in the radial areas 

 are large and regularly hexagonal and are arranged in 

 regular longitudinal parallel rows ; the plates are surmounted 

 by large flat-topped hexagonal granules of unequal size, which 

 fit close together to form a mosaic for each separate plate ; 

 abactinal surface of the rays formed principally by the 

 supero- marginal ])lates, which, however, are separated 

 throughout the ray by at least three rows of small irregularly 

 hexagonal paxilliforni plates. 



Marginal plates massive, closely covered with hexagonal 

 flat-topped granules, and forming on both aspects a very 

 broad border to the disk and rays ; they number thirty-five 

 in each series, and the two series correspond plate to plate ; 

 the infero-marginals of the interbrachia have a median 

 vertical series of distant papilliform spinelets or pedicellariie. 



The large adambulacral plates liave each a radiating 

 furrow-series of seven or eight flattened prismatic spinelets, 

 slightly decreasing in size in each series from the ends to the 

 middle, and actinally three unequal longitudinal series of 

 close prismatic granules. Mouth-plates narrow and elongate, 

 each with a furrow-series and a suture-series of coarse papilli- 

 form spinelets^ which increase in size from periphery to 

 centre. 



