22 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



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 unsuitability 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 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. 



It must be remembered, however, that Mr. 

 Stanley Gardiner has suggested that the Maldive 

 Coral Islands have grown up from a platform of 

 continental rock — part of the ancient land connection 

 which in the Secondary period is supposed to have crossed 

 the Indian Ocean from Ceylon to Madagascar, and which 

 in the early Tertiaries may have been reduced to a chain 

 of large islands. If that view is correct the interesting 

 question arises — Must we conclude that the considerable 

 number of bottom-living animals that are now common 

 to Ceylon and the Maldives have been carried across the 

 400 miles of deep sea either in the adult or the larval 

 condition since the coral archipelago was formed, or is 

 it possible that any of them have continued to live on the 

 Maldive plateau since the time (say in the early Eocene 

 period) when it was last connected with the continent of 

 India ? This is one of the Oceanographic problems in the 

 * See also, Stanley Gardiner, Annals and Mag. Nat. Hist., for Dec, 1904. 



