vol.. XVI, 



1H!»:{. 



] l'R()(M',i;i)IN(JS OF TIIK NATfONAl. MlISKUM. 303 



\i/: 1!<»()(1, Albi'iiiiule, Cliiiilcs, J)imcaii, Ijiiidloe, rJaiiios, (Jlialliain, and 

 liiddati^ablc. 



It may be said i)orlia])s tliat tlio picsoncc of tlie marine mollnscaii 

 forms of the West American coast is mncli less <lif(icidt to account i'or 

 llian citlier <d' tlie other faunal elements. 



DISTIillUITION OF TERRESTRIAL SPECIES. 



The di.stribulion of the terrestiial species ])otli by fbiviatile and 

 marine currents as well as by aerial forces is easily (explained. It in- 

 cliides necessarily a consideration of the vitality of these animals as 

 well as of their ej^f-s, 



Rinney,* referring to the introduction of forei^ni species into the 

 United States, says: "Oceanic currents also aid in bringing to our 

 shores foreign species, and have been the means of introducing and 

 natnializing them. The- (Inlf Stream is a prominent exain])le of this. 

 This great body of water, tiowing from the (lulfof Mexico into the 

 Atlantic, passes between the peninsula of Florida and the island of 

 Cuba, and after turning the soutiiern ]»oint of Florida sweeps along its 

 eastern shore. Jt is sometinu's driven close to the northern coast of 

 Cuba, and sometimes forced much farther north, according to the 

 direction and force of the wind. Various countercurrents, due also 

 to tho intluen(!e of the wind, diverge from the main stream, among 

 which is noticed a current, which, .ifter a northerly wind lias i)revailed 

 for several days, sets in a southwesterly direction near the Florida 

 lleef. The ju-incipal stream and the currents origiiuiting in it bear 

 upon the surface various vegetabh; and other i)roductions brought by 

 rivers into the Gulf or swept from its shores, and these are frequently 

 de])osited up<m parts of the coast very distant from their origin. In 

 this way seed vessels from the S[)anish Main, trunks of trees, aiul frag- 

 ments of wood of unascertained origin, and numerous objects from the 

 northern shore of Cuba are frequently found on the shore of Key 

 West and on the beach of Cape Florida and the shores and islands to 

 the north of it. 



"A few >earssincea bottle was picked up on Tavernia Key, near 

 CajK' Floiida, containing a note stating that it was tlirown overboard 

 otf the Moro Castle. A (yuba barge, of the kind used in lading and 

 unlading vessels in Matanzas, was lately found stranded on the beach 

 at New liiver, 2o miles noith of ( -ajx' Florida. Small objects from Cuba 

 are often ibund on the shore of Key West. 



"These circumstances are adequate to account lor the transnjission 

 of land shells from the island of Cuba, and even from more distant 

 places, to the mainland and islands of Florida; and to this sourc<' we 

 ascribe the origin of Helix, rhodocheila, and BuUmua virffulatus, which 



* Terr. Moll, and Slit-lls of Iho I'uited Statci.s (A. Hjuiicy) \'ol. i, 1S.")1, i». ir>2(l seq. 

 (edited by A. A. Gould). 



