204 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETT. 



COMPARISON OF HAULS. 



The results which we print (Forms 17 and 18) of the 

 hauls obtained on April 9th and 10th in Fort Erin Bay 

 are good examples of a local plankton mainly composed 

 of Diatoms. It will be noticed in running the eye down 

 the groups in Form 17 that whereas the Diatoms occur in 

 thousands extending up to even 100,000, the Dinoflagel- 

 lates are in hundreds, extending, at most, to a thousand ; 

 the Copepoda are in tens, rarely reaching a hundred or two, 

 while the fish-eggs are scattered units, such as 1 and 2. 

 The general character of these hauls on April 9th, then, 

 is that there are ten times as many Copepods as fish-eggs ; 

 ten times as many Dinoflagellates as Copepods, and ten 

 times as many Diatoms as Dinoflagellates, per species. 

 In Form 18, on the following day, the proportions are 

 somewhat the same ; and if we pick out the largest 

 numbers recorded in each of these groups they may be 

 described in the case of each day as units, hundreds, 

 thousands and tens of thousands. 



Diatoms Dinoflagellates Copepods Fish Eggs 



April 9 100,000 ... 1,000 ... 250 ... 2 

 April 10 90,000 ... 2,000 ... 780 ... 8 



As another example of the same run of figures in 

 these groups we note that in a surface haul, W. of the 

 Calf Island, on March 29th, the total 



Diatoms amount to ... ... ... 72,650 



Dinoflagellates ,, ... ... ... 8,500 



Copepoda ,, ... ... ... 363 



Fish Eggs „ 93 



Generally speaking these proportions hold good for 

 many of the series of hauls not only in the Bay, but also 

 outside; see, for example, Forms 20 and 21, below. 



It is also interesting to note that of these two series 

 of hauls taken in exactly the same spot on adjoining days, 



