KELATIONSHIP OF THE FAUNA. 89 



some of the peculiar land-snails of the Bermudas would be 

 drifted to our shores, where, with a favorable climate and vege- 

 table growth, they would soon multiply and spread, and to 

 such an extent as to make it appear as though they originated 

 on the continent. 



It might be objected that these seeming anomalies of dis- 

 tribution can be readily accounted for by assuming that there 

 has been simple artificial transport by means of vessels. And, 

 no doubt, full allowance must be made for this contingent dis- 

 tribution. But, again, on this assumption the absence of the 

 commonest species of land mollusks — those which have been 

 most broadly distributed over the earth's surface, and which 

 would have found congenial conditions of environment in the 

 Bermudas — becomes A'ery striking, and equally so whether we 

 consider the forms that may have been transported from the 

 Old World or from the New. 



The marine molluscan fauna of the Bermudas is, as has 

 already been seen, overwhelmingly Antillean in character, and 

 there can be no question that its own history is intimately 

 bound up with the history of the fauna of the West Indies. 

 The practically total absence of species of the Eastern United 

 States which are not found in the Floridian waters is astonish- 

 ing, and shows how insuperable is the barrier which the waters 

 of the Atlantic, arid of the Gulf stream particularly, offer to a 

 free migration or dispersion of the species. This, again, ap- 

 pears the more remarkable in the light of certain anomalies of 

 distribution which a critical examination of the species reveals, 

 and which had already in many cases been noted as a charac- 

 teristic of the West Indian fauna. Thus, the various species of 

 Triton, Triton cMorostoma, T. tiiherosum, T. cynocephalus and T. 

 pileare, are all members of the fauna of the Pacific and Indian 

 oceans; Ranella cruentata crops up in the variety R. rhodostoma, 

 from Mauritius. Again, Epidromus concinniis, from the Philip- 

 pines, is represented in our collection by a number of individ- 

 uals which are absolutely undistinguishable, both in shell or- 

 namentation and color-markings, from the Pacific specimens. 



