Safety 67 



parasites of various species of salmon in an attempt to determine 

 whether they showed marine or fresh-water affinities. He found that 

 European salmon were infested largely with marine parasites, but 

 that those along American shores carried mostly parasites that they 

 had acquired in fresh water. The results were therefore not very 

 conclusive. Trematodes belonging to the family Heterophytidae 

 occur in both the ocean and in fresh water. Stunkard & Shaw 

 (1931) have shown that some species in this family can complete 

 their life cycles in sea water or in nearly fresh water. 



The Vermillion spotted newt Triturus viridescens Raflnesque 

 passes through two phases during its life cycle. In its aquatic phase 

 it carries more parasites than in its terrestrial phase (HoU, 1932) . 

 In Japan the parasites of eight species of salamanders were studied 

 (Pearse, 1932f) . Some parasites were found only in aquatic and 

 others only in terrestrial hosts. On the whole there was little differ- 

 ence between the two types, except for cases due to host specificity. 

 Acanthocephalans and trypanosomes were found only in aquatic 

 hosts, which may seem natural, but it is hard to understand why 

 opalinid and flagellate parasites were found only in terrestrial types. 



At Tortugas the distribution of the parasites of crustaceans was 

 studied (Pearse, 1929, 1930a, 1932c). Most species of parasites 

 occurred in the intertidal zone, but most individual parasites were 

 found in hosts that lived on land. Epistylis, nematodes, barnacles, 

 copepods, isopods, rotifers, mites, and fly larvae occur as parasites 

 or commensals in the gills of crabs. At Tortugas and on the coasts 

 of China and Japan (Pearse, 1930a, b, 1931, 1932f) more parasites 

 were found in the gills of land crabs than in those of aquatic crabs, 

 but this was not true at the mouth of the Menam in Siam (Pearse, 

 1933a), where numerous barnacles lived in the branchial chambers 

 of certain species. In Siam and India more parasites were found 

 associated with aquatic than with land fishes (Pearse, 1932a) . 



There are many valid instances of animals which have left the 

 ocean to escape various dangers. However, there appears to be no 



