lii INTRODUCTION. 



shores of the Black Sea is as large and well developed 

 as the Arctic specimens. From Pondicherry, also, a 

 specimen is recorded that closely resembles the large 

 specimens of the northern type. 



The genus Gammarus, even as we have restricted it, 

 contains between forty and fifty species, all of which are 

 Arctic and north temperate, and extends round the globe, 

 except one taken at Jamaica, another at New Holland. 

 Fresh-water species of the genus inhabit the rivers and 

 streams of Europe and North America. Megamoera, a 

 near congener of Gammarus, has the largest and most 

 spinose species in the northern regions, while others are 

 found at Peru, Borneo, and the Zooloo seas. 



The genus Amphito'e contains between thirty and forty 

 species, and is very universally spread over the globe, 

 species having been taken in the Arctic seas and all round 

 the coast of Europe, in the Black Sea, and the Medi- 

 terranean ; they have been found at the Cape of Good 

 Hope, and on the eastern and western coasts of South 

 America, on the Australian shores, as well as in Zooloo 

 and Japanese seas, in the islands of the Pacific and 

 Atlantic Oceans, also on the weed in the Saragossa Sea, 

 of the Atlantic, and on floating plants in the Pacific ; and 

 one species is recorded from the fresh-water marshes of 

 South Carolina. 



Podocerus is mostly northern, extending, however, 

 down the coasts of Europe and America. One species is 

 recorded by Dana from the Bay of Sunda, and another 

 from the shores of Brazil. 



Cerapus, including its female, Leucothoe, has a wide 

 range, species having been taken on the European and 

 North American shores, on the eastern coast of South 

 America, and in the Indian and Zooloo seas, while its 

 near ally, SlphoncBCetus, has only been found on the north- 



