A REVIEW OF THE MYSIDACEA 



Table 1. — Forms of Mysidacea occurring off the coasts of America and the Atlantic 



coasts of Europe 



Genus 



Siriella 



Qastrosaccus 



Archaeomysis 



Anchialina 



Erythrops 



Mysidopsis^ 



Metamysidopsis.. 



Promysis 



Leptomysis 



Mysidetes 



Arthromysis 



Mysis 



Hemimysis 



Paramysis 



Praunus 



Mesopodopsis 



Neomysi.i 



Acanthomysis 



Mysiiium.. 



Proneomysis 



Paracanthomysis. 

 Heteromysis 



Total 



It will be observed that no fewer than 7 out of a total of 16 Amer- 

 ican genera are common to the two coasts, with 12 genera known from 

 the east coast and 11 from the west coast. This close parallel between 

 the two faunas is very striking. The most outstanding feature of 

 the west coast fauna is the predominance of the genera Neomysis and 

 Acanthomysis, represented by 9 and 7 species, respectively, out of a 

 total of 30. On the east coast, in contrast, only one species of 

 Neomysis and none of Acanthomysis is known. 



Mysis oculata, of all the littoral species, alone represents the Arctic 

 shallow-water fauna on the American coasts. It extends southward 

 along the east coast to Labrador, where Arctic conditions give way 

 to Boreal. It is the only species of coastal mysid known from the 

 Arctic shores of North America, and it extends right around those 

 coasts to Alaska, of which it just reaches the Pacific coast. 



Ii a comparison is made between the littoral species of the east coast 

 of America and those of the European coasts some interesting points 

 emerge. Three species only are common to the two areas — Mysis 

 oculata, Mysis mixta, and Heteromysis formosa. Mysis oculata, as 

 stated above, is an Arctic littoral species and in Europe it reaches the 



