A REVIEW OF THE MYSIDACEA 7 



the Atlantic is thus explained. The species found on the American 

 slope and not on the corresponding European shelf are : 



Lophogaster americanus Metamblyops macrops 



Lophogaster spinosus Synerythrops cruciata 



Lophogaster longirostris Bathymysis renoculata 

 Hypererythrops caribbaea 



All these species, with the exception of Synerythrops cruciata, are 

 represented on the European continental slope by allied species of the 

 same genera. There is, therefore, a much closer relationship between 

 the deeper water faunas of eastern America and Europe than between 

 the littoral and coastal faunas. 



From the cold-water area of the Arctic Ocean Hansen records 8 

 species of bottom-living mysids, and of these two approach the Ameri- 

 can coast: Boreomysis nobilis, which has been recorded from deep 

 water off the eastern coast of Labrador, and Amblyops ohlinii, from 

 1,060 to 1,081 fathoms off the northeastern coast of the United States. 

 They are the only representatives of the cold-water fauna of the Arctic 

 that reach American waters. 



The deeper-water fauna of the continental shelf of the Pacific slope 

 includes, besides the five species already mentioned above as found 

 on the Atlantic slope as well, the following species : 



Holmesiella anomala Amblyops hispida 



Pseudomma berkeleyi Inttsitatomysis serrata 



Pscudomma oculospinum Dactylamblyops sp.? 



The last five of these species are known only from one or two local- 

 ities, but Holmesiella anomala is an abundant species peculiar to the 

 Pacific coast, which has a wide distribution at suitable depths. 



Pelagic species. — There is only one upper-water, epiplanktonic, 

 often surface species of mysid that may be included in the American 

 fauna — Siriella thompsonii. Unlike the majority of species of this 

 genus, which are coastal in habit, S. thompsonii is definitely oceanic 

 and is usually caught at the surface, especially at night. It is widely 

 distributed in both the Atlantic and Pacific Oceans in the tropical 

 and subtropical zones. 



The other pelagic mysids of the American fauna are deep-water, 

 bathypelagic, mesoplanktonic forms, living usually at moderately 

 great depths and widely distributed in the great depths of the oceans 

 of the world. Twenty-four such species have been recorded from 

 American waters. Of these, eight have been recorded from both the 

 Atlantic and Pacific waters of America : 



Gnathophausia ingens Eucopia unguiculata 



Gnathophausia gigas Petalophthalmus armiger 



Gnathophausia zoea Euchaetomera typica 



Eucopia sculpticauda Euchaetomera tenuis 



893476—51 2 



