224 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The Copepoda are remaining fairly constant, while 

 the Diatoms, having passed their spring maximum, arc 

 falling oft rapidly. 



On Forms 16 ; 19, we give the results of hauls taken 

 on the along-shore station III, off the Slock, on two 

 adjoining' days, April 9th and 10th. The two surface 

 hauls are very unlike in quantity, although practically 

 the same series of organisms is represented. Such 

 numbers as 37,000 to 1,500; 4,000 to 250; and 19,000 to 

 550 indicate a considerable disproportion. The surface 

 plankton, then, if we may judge from these two samples, 

 had fallen on April 10th to less than half what it had 

 been on the previous day. But if we compare the two 

 hauls taken on April 10th, w r e find that the second net 

 towed simultaneously with the first, but at about a fathom 

 below the surface, yielded a much more abundant 

 gathering. On looking into the details one finds that all 

 the Diatoms and Ceratium trijios are more numerous in 

 the deeper haul, while the larger organisms — Medusae, 

 Larvae, Copepoda, and Oikopleura — are more abundant 

 on the surface. Some of the Diatoms showed a great 

 increase below the surface, the extreme case being 

 Chaetoceros contortum with 120,000 at one fathom to 1,500 

 at the surface. 



On the other hand during the later summer we met 

 with cases where the Copepoda and other larger organisms 

 w r ere much more abundant in a zone below the surface. 

 Here is an example (Form 84) from off-shore station II, on 

 August 27, where the weighted net brought up 7*5 c.c. 

 as asrainst 1 c.c. in each of the surface nets -all three nets 

 being alike and used simultaneously. The relatively 

 large numbers of Acartia, Pseudocalanus, and Copepod 

 TS T auplii. will be noticed. The two surface nets on this 

 occasion yielded identical quantities, but the detailed 



