20 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



to me to, institute a comparison between the animals of 

 Ceylon and those of the Maldive archipelago recently 

 explored by Mr. Stanley Gardiner. Ceylon is geologi- 

 cally and zoologically a part of the continent of India, 

 while the Maldives are usually supposed to be a group of 

 Oceanic Coral Islands. A comparison between a shallow 

 water Continental Coast fauna and that of a group of 

 Oceanic Coral Islands only, on the average, some 400 miles 

 apart, in the same latitudes and the same sea, but 

 separated by deep water, ought to be instructive. In 

 comparing the numbers of animals in the chief groups 

 from the two regions there are marked differences, some of 

 which seem susceptible of explanation. A group of 

 Oceanic Coral Islands must clearly have been populated 

 from some of the surrounding older continental coasts, 

 and the nearest of these to the Maldives are Ceylon and 

 the southern end of India, some three to five hundred miles 

 distant. There are two dominant factors that naturally 

 play an important part in determining which animals from 

 the neighbouring continent will form part of the new 

 population, viz. : — (1) the means of transport possessed by 

 the animals either in the adult or the larval condition, 

 and (2) whether or not the conditions existing on the 

 island are sufficiently favourable to the migrating animal 

 on its arrival either as an adult or a larva. 



Looking at the lists which are given in my Ceylon 

 Report (Vol. V., p. 436) we find that the total number of 

 animals is much greater in the recorded Ceylon fauna 

 than in that of the Maldives, but that in certain groups — 

 the Medusae, Actinozoa, Gephyrea, Cirripedia and Macrura 

 — the Maldivian numbers are the greater; while in other 

 groups — such as Hydroida, Alcyonaria, Echinodermata, 

 Platyelmia, Copepoda, Amphipoda, Isopoda and Mollusca 

 — the Ceylon list markedly predominates. 



