54 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the prevailing forms. In the second haul Coscinodiscus 

 concinnus was the chief constituent. In the third haul an 

 abundance of Eucampia zodiacus and a fair quantity of 

 Rhizosolenia was found. The fourth haul was very 

 similar to the first. Copepoda were comparatively scarce 

 throughout the traverse and consisted mainly of 

 Paracalanas and Oithona. The first haul contained one 

 Calanus and six Temora. Temora was not taken again, 

 and the second and third hauls had no Calanus. The 

 fourth haul contained eight Calanus. Amongst other 

 things, Noctiluca and Sagitta were tolerably common in 

 the four hauls. 



The cruise was continued to the West side of the 

 Isle of Man. Six miles N. from Peel another haul was 

 taken, which revealed a complete change in the plankton. 

 The quantity measured \ c.c, and in it were three Sagitta 

 and sixteen Calanus. Pseudocalanus, Acartia, and 

 Oithona were tolerably common. Four genera of diatoms, 

 each represented by a very few specimens, a few larval 

 PolychaBta, Ceratium tripos and C. fusus, and " Mitraria," 

 but no Noctiluca, were taken. A quantitative estimation 

 of the plankton obtained during that particular cruise is 

 of course possible; but to say that every cubic metre 

 traversed contained a definite number, or even an average 

 number of Coscinodiscus, Rhizosolenia, Calanus or Temora 

 would be unjustifiable and misleading. 



The Naturalist's Dredge. 



