CRUSTACEANS OF THE ORDERS EUPHAUSIACEA AND 

 MYSIDACEA FROM THE WESTERN ATLANTIC 



By Walter M. Tattersall 



Professor of Zoology, University College, Cardiff, Wales 



INTRODUCTION 



Dr. H. B. Bigelow was good enough to submit to me for examina- 

 tion and report the Euphausiacea and Mysidacea collected in the 

 west Atlantic by the United States Coast Survey steamer Bache in 

 January to March, 1914. The collection contained 27 species of 

 Euphausiacea and 11 species of Mysidacea, while from the point of 

 view of numbers it was an extremely large collection. 



The itinerary of the cruise of the Bache, together with a full account 

 of the oceanographical results obtained, has already been published 

 (Bigelow, 1917a), but for the sake of convenience a list of the stations 

 at which Euphausians or Mysids were taken is given on pages 4-6. 



The area explored during this cruise has never before been sys- 

 tematically examined for the Crustacea here reported on, although 

 a large number of disjointed and scattered records are to be found in 

 literature. Hansen (1915) has given a great many records of Euphau- 

 siacea from the west Atlantic, mainly, however, in the northwestern 

 part of the area now under consideration. Ortmann (1893) records 

 certain species from or near to this area, taken during the German 

 Plankton Expedition, and Colosi (1920) adds a few records from the 

 Caribbean Sea. The present collection, however, by linking up 

 hitherto explored areas, adds considerably to our knowledge of the 

 occurrence and distribution of the Euphausiacea in the west Atlantic 

 and, incidentally, and to a lesser degree, of the Mysidacea also. 



Only one new species was discovered, a Mysid, Ilysidopsis higelowi, 

 from the littoral waters of Chesapeake Bay. The most interesting 

 species taken by the expedition was the Mysidacean, Paralophogaster 

 glaher Hansen, hitherto only known from the Pacific Ocean, near the 

 Dutch East Indies, and in the waters off New Zealand. Its discovery 

 in the western Atlantic is therefore most interesting from the point 

 of view of geographical distribution and demonstrates the wide range 

 of this bathypelagic species. Other notable records are those of the 

 larvae of a large species of Thysanopoda and of the adults of Nemato- 

 hrachion sexspinosus Hansen^ hitherto known from three specimens 

 only. 



No. 2634.— Proceedings U. S. National Museum. Vol. 69, Art. 8. 

 3043—261 1 1 



