154 Proceedings of the Royal Physical Society. 



XVIII.— The Marine Fauna of the Mergui Archipelago, Lower 

 Burma, collected by James J. Simpson, M.A., B.Sc, and R. N. 

 Rudmose Brown, D.Sc, University of Aberdeen, February till May 

 1907. The Ophiuroidea. By Donald C. M'Intosh, M.A., B.Sc., 

 F.R.S.E., Research Student, University of Edinburgh. 



(Read 27th February 1911. Received 27th February 1911.) 



I.— INTEODUCTION. 



The material which forms the subject of the present communication was 

 collected by Mr Jas. J. Simpson and Dr Eudmose Brown in 1907, while they 

 were investigating, on behalf of the Indian Government, the pearl-oyster 

 fisheries of the Mergui Archipelago. 



Our knowledge of the Ophiuroidea of the Indian Seas has been greatly 

 extended within recent years by accounts which various workers have 

 published, and in particular by Professor Koehler's (1898) report on the 

 collections made by the " Investigator " in 1896. The only published record, 

 however, of Ophiuroidea exclusively from the Mergui Archipelago, is Professor 

 P. Martin Duncan's description, in the Journal of the Linnean Society for 

 1886, of the collections by Dr J. Anderson in that locality in 1882. Of the 

 thirteen species, in addition to some young unidentified forms of Ophioglypha, 

 in Professor Duncan's list, all were new, except the following four species, 

 Opliiolepis cincta Miiller et Troschel, Ophiocnemis marmorata (Lamarck), 

 Ophiocoma scolopendrina (Lamarck), and Ophiothrix martensi Lyman, which 

 are well known, and have been repeatedly recorded from the Indian Ocean 

 and the neighbourhood of the Western Pacific Islands. It is not a little 

 remarkable that while the present collection contains three of these four 

 species, it contains only one of Duncan's new species, viz., Ophiocampis 

 pellucida, for Ophiothrix variabilis Duncan, is now regarded as synonymous 

 with 0. hirsnta Miiller et Troschel. Yet four of Duncan's species, first 

 described from Dr Anderson's collection, have since been found elsewhere in 

 Eastern seas, one species, Ophiocampis pellucida, by the " Investigator," and 

 three species, Ophiolepis nodosa, Ophiocnida sexradiata and Ophiothrix 

 andersoni by the " Siboga " expedition (Koehler, 1905). 



In the present collection there are seventeen species, amongst which 

 the Zygophiurse are represented by fifteen species (five families), and the 

 Cladophiurae by two species. Ten of the species, including such forms as 

 Pectinura yorgonia, Ophiocoma scolopendrina, Ophiothrix foveolata and 

 Ophiothrix stelliycra, are well-known inhabitants of the Indian and Eastern seas, 



