220 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



points of difference. We may add that in the haul of the 



shear-net, taken at the same place and time, there were 



1,380 larvae of Pectinaria in tubes along with 5,400 

 Balanus nauplii, and many other organisms. 



Net B= 16 c.cm. Net C= 155;c.cm. 



Larval Polychaeta 650 ... 



Balanus nauplii 3,000 ... 



„ cypris stage 50 ... 



Copepoda nauplii 7,000 ... 2,000 



juv 13,000 ... 



Calanus helgolandicus 100 ... 6 



Pseudocalanus elongatus 850 ... 500 



Temora longicornis 2,470 ... 4,750 



Oithona similis 100 ... 50 



Acartia clausi 250 ... 200 



Centropages hamatus ... 200 



Coscinodiscus concinnus 8,000 ... 14,000 



Biddulphia mobiliensis 40,000 ... 70,000 



Rhizosolenia semispina 1,000 ... 3,000 



Lauderia borealis 1,000 ... 



Thalassiosira nordenskioldii ... 2,000 ... 7,000 



subtilis 6,000 ... 



Chaetoceros teres ... 1,000 



Peridinium sp 500 ... 



Plutei 500 ... 1,000 



Oikopleura sp 2,000 ... 150 



Medusoids 50 ... 25 



Sagitta bipunctata ... 48 



Crab zoeas , ... 10 



This shows very clearly that the two gatherings, 

 although alike in quantity, were unlike in quality. 



Another example (Form 41) is given here from April 

 19th, where the catch in each case was 18 c.c, but the 

 amount is made up in very different ways. Out of a total 

 of 38 organisms in the two surface nets there are nine 

 which are absent from one or the other net. Of those 

 present in both the numbers differ notably in a few cases, 

 such as 1,000:4,000; 1,000:3,000; and 500:3,000; in 

 other cases again, such as " Mitraria " and Copepod 

 nauplii, the numbers agree exactly. It will be noticed that 

 the Nansen net caught more than the Hensen — both fishing 

 through the lower half of the water (20 to 10 fathoms) — 

 and that the weighted net, ranging through the upper 



