28 Proceedings of the Royal Physical Society. 



17. Fromia milleporella, Gray. 



18. Retaster cribrosus (von Mart.). 



19. Fchinaster purpureus (Gray), Bell. 



The absence of any species of Linckia is noticeable, for this genus is widely 

 diffused and common in many parts of the Indian Ocean. Three species 

 constitute new records for the Indian Ocean, namely, Craspidaster hesperus, 

 a Pacific species, and Anthenea flavescens and Pentaceros granulosus, both 

 Australian forms. Pentaceros gracilis is extremely abundant on the pearl 

 banks of the Mergui Archipelago, and has since been noted in numbers on 

 the pearl banks of the Mozambique coast of Africa ; yet, as far as I can 

 ascertain, it was previous to these discoveries looked upon as an Australian 

 form ; a fact which forcibly illustrates the poverty of our knowledge of the 

 marine fauna of many parts of the Indian Ocean. 



1 . Archaster typicus, M. & T. 

 Perrier, Revision de Stellericles, 1 Arch, tie Zool. expdr. et gen., v. (1875), p. 265. 



Locality. — XVI., Alligator Rock, 8 to 18 fathoms, rock and sand. 



Two specimens in which it = 44 and 46 and r=10 and 9 respectively. 2 

 In the smaller specimen a single spine appears on one supero-marginal ; 

 otherwise the supero-marginals have no trace of spines. A similar occurrence 

 in this species is noted by Liitken (Vidensk. Medd. (1864), p. 136), and 

 by Sladen ("Challenger" Reports, xxx., p. 124). 



This species is also recorded from the Mergui Archipelago by Dr Anderson 

 in 1882. Widely distributed in Eastern Indian Ocean and Western Pacific. 



2. Craspidaster hesperus (M. & T.), Sladen. 

 Sladen, "Challenger" Reports, xxx. p. 177, pi. xvii. tigs. 5-7 ; and pi. xviii. figs. 1-4. 



Locality. — XXXII., Off Bentinck Island, 29 fathoms, soft mud and sand. 



Two specimens agree with the young phase described by Sladen. The 

 adpressed spinelets on the infero-marginal plates tend to fall off very readily, 

 but their presence is quite evident in both specimens. 



R^-22 r=6'5. 



Apparently not previously recorded from the Indian Ocean. Known from 

 Japan to Singapore. 



1 In the case of species included in Perrier's Revision, I give no other reference than 

 to his paper as a rule : the synonymy is therein discussed. 



2 All measurements are in millimetres, 



