SOME PROBLEMS OF THE SEA. 21 



Oceanic or pelagic groups, as would be expected, 

 and coastal animals of active habit, possessing the 

 necessary means of transport in the adult condition are 

 well represented in the Maldive fauna. For example, 

 Fishes, Medusa? and Chaetognatha are all fairly abundant. 

 The Cirripedia also, some of which are almost cosmo- 

 politan in their distribution on the high seas, are more 

 numerous than in Ceylon. The Copepoda might be 

 expected to bulk larger than they do. The pelagic and 

 more active forms are, however, present, and the 

 deficiency is in the bottom-living species, many of which 

 are associated with Sponges, Tunicates and other fixed 

 colonies which are probably much more abundant at 

 Ceylon than in the Maldives. The high number in the 

 case of Actinozoa is due to species of Madreporaria which 

 are, of course, abundant in a coral archipelago, and the 

 species of which were especially studied by Mr. Stanley 

 Gardiner. In the case of Macrura, the 79 species include 

 76 Alpheidse, and the species of Alpheus, being closely 

 associated in habitat with corals, would naturally be 

 obtained in abundance amongst the reefs. 



Turning to the other groups of animals which are 

 more abundant at Ceylon, we find that it is the fixed and 

 the more or less sedentary, bottom-living forms that are 

 poorly represented in the Maldivian fauna, e.g., Hydroida, 

 Alcyonaria, Echinodermata and Mollusca. I should expect 

 this to apply also to Sponges, Polyzoa and Tunicata, but 

 these Maldivian groups have not yet been reported on. 

 Most of these groups are dependent for dispersal upon 

 minute, feeble and short-lived embryos or larvae, to which 

 400 miles of open sea may be a formidable obstacle. 



In marked contrast to some of these groups there is the 

 case of the Brachyura, where the numbers in the two 

 faunas (Maldives 184 and Ceylon 208) are not very 



