FAUNTSTIC RESULTS. 437 



habit, possessing the necessary means of transport in the adult condition, are well 

 represented in the Maldive fauna. For example, Fishes, Medusae, and Chaetognatha 

 are all fairly abundant. The Cirripedia also, some of which are almost cosmopolitan 

 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 includes 

 76 Alpheidse, and the species of Alpheus being closely associated in habitat with 

 Corals would naturally be obtained in abundance amongst the reefs. 



Turning now to the 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, Echinoderma, 

 and Mollusca. I should expect this result to apply also to Sponges, Polyzoa, and 

 Tunicata, and I have little doubt that it does, but these groups in the case of the 

 Maldivian fauna 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 189 and Ceylon 208) are not very different. The probable 

 explanation is that the larvae of the crabs are powerful, locomotory, comparatively 

 long-lived animals which are frequently taken in the tow-net in the open sea, and are 

 therefore much better fitted to survive the journey from the continental coast. The 

 most feebly represented of Crustacean groups are the Amphipoda and Isopoda, and I 

 would suggest that the explanation is to be found in the un^.uitability of their young 

 stages for distribution to oceanic islands. Those that do cross in safety are probably 

 carried accidentally on larger objects. It may conceivably be easier for a shallow- 

 water species, which neither in the adult nor in larval life is adapted to a prolonged 

 pelagic existence, to spread in the course of ages from India to Australia along the 

 stepping-stones of Malaysia than to cross the stretch of open sea from Ceylon to the 

 Maldives. 



There is, however, not only the numerical but also the specific constitution of the 

 two faunas to be considered, and, undoubtedly, many species are common to the 

 Maldives and Ceylon. Probably all the Corals collected in the Gulf of Manaar have 

 been recorded in Mr. STANLEY GARDINER'S reports, and nearly all their associated 

 Alpheidae. The Foraminifera seem to be very much the same in the two localities, 

 at corresponding depths. Out of 131 species found at Ceylon, 68 occur in CHAPMAN'S 

 list from the Laccadives, and the latter collection was mainly, if not wholly, a deep- 



