GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 1557 



The propriety of uniting in one kingdom both coasts of America, 

 the eastern and western, and thus shutting off the latter from the 

 great Pacific Ocean, may at first appear unnatural. Yet it is sup- 

 ported by all facts bearing on the subject. There are no species known 

 to be common to Western America and the Middle Pacific, excepting 

 two or three cosmopolites. Moreover, the genera are to a great extent 

 distinct, and where so, they often occur on both sides of the continent. 

 The genera of Podophthalmia peculiar to America are mentioned on 

 page 1548, and also the particular coast on which they occur. 



A review of some of the facts will exhibit in a strong light the 

 zoological resemblances of the two sides of the continent. 



Of Cancer, there are four species found on the west coast of South 

 America, three on the west coast of North America, and two on the 

 east coast of North America. 



Of Hepatus, there is one species common to the West Indies and 

 Brazil, a second, found at Rio Janeiro ; a third, at Valparaiso, Chili ; 

 & fourth, on the Carolina coast. 



Libinia, in the same manner, has its species on the Atlantic and 

 Pacific coasts of the United States, and the coasts of Western and 

 Eastern South America. Mithrax is as widely distributed. 



Epialtus occurs in the West Indies, California, Brazil, Gallapagos, 

 and Valparaiso, fbtamia has two West Indian and one Chilian species. 



Eurypodius of Southern South America has its representative at 

 Puget's Sound, in the genus Oregonia. 



Again, the Libinia dubia of the West Indies, is hardly distinguish- 

 able, according to Prof. L. R. Gibbes, from the L. affinis, Rand;, of the 

 California coast. L. spinosa of Brazil is also found in Chili. Lepto- 

 podia sagittai-ia'joccurs in the West Indies, and also, according to Bell, 

 at Valparaiso; Acanthonyx Petiverii (?), in the West Indies, Brazil, 

 and Gallapagos ; Epialtus marginatus, on the coast of Brazil and at 

 the Gallapagos (Bell) ; Epialtus bituberculatus, in Chili, and at Key 

 West ; Uca una, Guayaquil and West Indies; Albuncea scutellata, West 

 Indies and San Lorenzo, Peru ; Hippa emerita and talpoides, both 

 on East and West America, North and South. 



It is obvious, therefore, that the east and west sides of America are 

 very closely related, arid differ widely in a zoological sense, from 

 either of the other kingdoms. 



We observe further, that nearly all the genera peculiar to America 

 are cold-water genera. They are mostly Maioids ; the large group of 



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