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CHAPTER XL. 



ox THE GEOGEAPHICAL DISTEIBUTION AND MIGRATIOjNT 01 



SPECIES — continued. 



GEOGRAPHICAL DISTRIBXJTIOK AKD MIGRATION OF FISH — OF TESTACEA 



OF INSECTS MOTHS SEEN FLYING 300 MILES FROM LAND — BOTANICAL 



GEOGRAPHY DISPERSION OF PLANTS — AGENCY OF RIVERS AND CURRENTS 



MARINE PLANTS — SARGASSUM OR GVLF-TiV^EED — AGENCY OF ANIMALS IN THE 

 DISTRIBUTION OF PLANTS— AGENCY OF MAN, BOTH VOLUNTARY AND INVOLUN- 

 TARY, IN THE DISPERSION OF PLANTS. 



Geographical distribution' and migration of fish. 



Althongli we are less acquainted with tlie habitations of 

 marine animals than with those of terrestrial species^ yet i 



is Avell ascertained that their distribntion is governed bj the 



same 



compa 



ing the freshwater fish of Europe and North 

 America, Sir John Eichardson remarks, that the only species 

 which is unequivocally common to the two continents is the 

 pike {Esox lucms) ; and it is curious that this fish is unknown 



Mountains 



1 



a^^proaches nearest to the old continent."^ According* to the 



same 



agree 



closely with those of the peninsula of India, but the species 

 are not the same. ^As in the distribution^ he adds "^of 

 marine fish, the interposition of a continent stretching* from 

 the tropics far into the temperate or colder parts of the ocean 

 separates different ichthyological groups ; so with respect to 

 the freshwater species, the intrusion of a 



'ms of the 



sea 



running far to the northwards, or the interposition of a lofty 

 mountain-chain, effects the same thing. The freshwater 

 fish of the Cape of Good Hope and the South-American 



Histo 



t 



VOL. II. 



Brit. Assoc. Eeports, vol. v. p. 203. 

 t Eeportto the Brit. Assoc, 1845, p. 192 



B B 



