LARVAL TRANSPORT BY OCEAN CURRENTS 



467 



Fig. 2. Prosobranch larvae of the long distance type. A, B, and C, larvae of 

 Tonna sp. taken off Bermuda (Lebour, 1945) ; D, larva of unknown prosobranch 

 from the China Sea (Dawydoff, 1940). 



Mid-water metamorphosis is rare. Their chances of dispersal are 

 hardly better than indicated in Fig. 1, and even transports over 

 fairly small sea areas may be a serious problem. It is in good 

 agreement with Ekman's (1953, p. 19) statement for Hawaii that 

 "especially the mussels are largely endemic." Among all the groups 

 studied this seems to be the one most unfit for long-distance 

 transportation. 



In decapod crustaceafis the majority of the larval species also 



