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CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



around these islands are almost constantly from the southeast, 

 the fern flora should be most closely related to that of the cen- 

 tral and southern part of South America. Such is not the case, 

 however, for outside of fifteen species which are of wide distri- 

 bution, the fern flora shows nearly as strong affinities with that 

 of Mexico as it does with that of South America. There are 

 on the islands fifty-four species common to Mexico and fifty-six 

 to South America. Moreover, the majority of the latter belong 

 only to the northern part of the continent. 



Devices for wind dissemination are not common on the seeds 

 of Galapagos plants, the Compositae being the only one of the 

 larger families which has this character pronounced to any 

 extent. 



Oceanic Currents 



The northern islands of the group, viz. Abingdon, Bindloe, 

 Culpepper, Tower, and Wenman, lie in the direct path of the 

 Panama current, and the water surrounding them is several 

 degrees warmer than that around the southern islands, which 

 are bathed by the Humboldt current. If oceanic currents were 

 an important factor in the transport of seeds to the Galapagos, 

 those islands which are washed by the Panama current should 

 be more closely related botanically to the Mexican and Central 

 American regions than the islands lying in the Humboldt 

 current ; and the latter islands, on the other hand, should have a 

 flora more closely related to that of the western coast of South 

 America. Furthermore, the several islands of each group 

 should have a larger floral element common among themselves 

 than with any of the islands of the other group. The following 

 table shows the percentages of floral relationships between the 

 islands of the northern group, as well as their relationships with 

 some of the more important islands of the southern group. 



