8 BULLETIN" 2 01, UNITED STATES NATIONAL MUSEUM 



Those recorded only from the Atlantic waters are : 



Paralophogaster atlanticus Meterythrops picta 



Petalophthalmus oculatus Longithorax capensis 



Boreomysis microps Katcrythrops oceanae 



Those known only from the Pacific side are : 



Chalaraspidum alatum Boreomysis inermis 



Gnathophausia gracilis Boreomysis californica 



Gnathophausia zoea var. scapularis Boreomysis rostrata 



Scolophthalmus lueifugus Caesaromy sides Uguriae 



Ceratomysis spinosa Doxomysis microps 



It should perhaps be mentioned that Euchaetomera typica, E. 

 tenuis, and Doxomysis microps are not strictly bathypelagic but may 

 and do occur at lesser depths, even sometimes at the surface. 



Surveying the mysidacean fauna of America as a whole, we may 

 suggest that the east coast of North America, from New England to 

 the Gulf of Mexico and the west coast from Alaska to California are 

 respectively two continuous and homogeneous faunal areas, in both 

 the littoral and the deep-water fauna. The evidence is not very 

 conclusive, for intensive investigation of the littoral fauna of the east 

 coast south of New England has still to be carried out. This may 

 reveal a number of species not found in the already well-known area 

 off the New England coast. On the west coast the areas around San 

 Francisco, British Columbia, and Alaska have been more closely 

 worked and the distribution of the species of littoral mysids indi- 

 cates a continuous faunal area extending from Alaska to San Fran- 

 cisco as shown in table 2. 



Table 2. — Distribution of littoral species of Mysidacea from Alaska to California 

 and from British Columbia to California 



1 Or even farther south. 



HISTORY OF AMERICAN MYSIDACEA 



The growth of our knowledge of the Mysidacea of America has been 

 a slow and gradual process extending over just a century. The first 

 record was published in 1841, when Gould recorded My sis spinulosus 

 from the shores of Massachusetts. This was followed in 1844 by the 

 record of the same species from New York State by De Kay. Both 

 these records in all probability refer to the species now known as 



