68 COPEI'ODA — METRIDIA 



From the occurence in April 1899 it appears that it enters the 

 Atlantic west of the Cape of Good Hope. In December 1897 to 

 February 1898 it occurred both from the Azores to the European 

 ■coast, in the Caribbean Sea and in the Florida Current. In March 

 it appeared suddenly over a very wide area round the Sargasso Sea 

 and across the whole Atlantic, from the Engl. Channel to the east 

 of New York. Later it decreased in abundance, but in November it 

 reappeared over the wide area between 40" and 50' N. from 20° W. 

 towards New York. As it is impossible to account for these sudden 

 changes in the distribution by surface currents, the most acceptable 

 explanation seems to be that water, containing this species (or Styli- 

 plankton) arrived in the spring by a vertical movement to the sur- 

 face, but in April and May was covered by another kind of water, 

 that remained between 40° and 50° N. to November. That other 

 kind of water cannot be any other than water containing Desmo- 

 plankton and arrived as a surface-current from the Florida Current 

 and the Sargasso Sea. — 5. 



METRIDIA HIBERNICA (Brady & Roberts) 



1898 February: 50° N. 31° W.; 48° N. 41° W. 

 March: ^t"" N. 27° W. to 50° N. 9° W. 

 May: 42° N. 61° W. 



June: 45° N. 41° W. 



November: 52° N. 38° W.; 56° N. 26° W. 



December: 50° N. 20°— 9° W. 



1899 March: 62° N. 8° W. 



June: 62° N. 0° 37' E., below 100 metres. 

 July: 56° N. 15° W., rare. 

 September: 62° N. 0° 40'— 1° E. 



Temperature: ll.i, mean of 11 obs., max. 16.3, min. 6. 



Salinity: 35.25, mean of 10 obs., max. 36.02, min. 32.96. 



Plankton-type. Noted from Iceland, the Faroe Channel, the 

 North Sea, the Skagerak and the west coast of Norway, at least 

 to 71° N. It occurs in the Atlantic usually associated with Tricho- 

 plankton, — (7.) A^s. 



