FAUNISTIC RESULTS. 



435 



' Journ. Linnean Soc., Zool.,' vols. xxi. and xxii.), (2) the series of Reports and " Illustra- 

 tions " issued from the Calcutta Museum as the result of work by Colonel Alcock 

 and others in the " Investigator," and (3) Mr. Stanley Gardiner's series dealing 

 with "The Fauna and Geography of the Maldive and Laccadive Archipelagoes." 

 The map (fig. 1) will serve to recall relative positions and distances. 



The Mergui marine fauna is, as might be expected, not unlike that of Ceylon, but 

 differs in the details of the species that occur. It is, however, if we may judge from 

 the published records, not so rich a fauna, as the following summary will show using 

 only those groups which are common to the two reports. The predominance of 

 Actinozoa, in the case of Mergui, is due to the large number of species of Corals 

 described by Professor Martin Duncan. The other groups of fixed organisms 

 Sponges, Hydroids, Alcyonaria and Polyzoa show markedly in favour of Ceylon. 



As an indication that the fauna of the Indian Ocean is gradually becoming known, 

 in, at least, some groups, it may be noted that in Dr. de Man's account of the 

 Mergui Podophthalmata (1888) out of 166 species, 38 (about 23 per cent.) were new 

 to science, while 18 years later, in the present report, out of the much larger number 

 (321) of Ceylon Podophthalmata, only 22 (less than 7 per cent.) were previously 

 unknown. In Brachyura, 39 species (nearly ) are common to the two lists. 



Colonel Alcock's magnificent series of monographs and the accompanying fasciculi 

 of " Illustrations," have done much to elucidate the fauna of the northern part of the 

 Indian Ocean, but they deal largely with deep-water forms, and I find it difficult to 

 make any comparison between my restricted, but, perhaps, more intensive, study of a 

 small shallow-water area (the Gulf of Manaar) and his extended gleanings all over 

 the three seas of India. Perhaps the most important conclusion to be drawn is the 

 extreme richness of the fauna, since so little is common to the two series of results. 

 Some groups have not yet appeared in the "Investigator" series, but even in the 

 case of those that have been monographed, the shallow waters of Ceylon have here 

 and there added something to the list. These reports cannot be compared in number 

 of novelties with the " Investigator " monographs, but they may be regarded as in 

 some respects supplementing them. 



The comparison with the Maldive fauna ought to be more satisfactory and 

 interesting : first, because Stanley Gardiner's reports are almost as recent as 



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