SEA-FISHERIES LABORATORY. 2138 
net was small enough to catch all the smaller fish present, 
and it is otherwise highly probable that no plaice much 
less than 4 centimetres in length could have been present 
at the time. On the other hand, the upper limit is 
indefinite, since the larger plaice were easily able to 
swim back out from the net on account of the restricted 
draught of water through the narrow meshes. We know, 
of course, that larger plaice than those caught must have 
been present on the ground. The form of the curve does 
not, of course, mean that the plaice were infinitely large, 
but just that the decrease in the numbers captured varies 
as if the range were infinite. 
Tyrpr VI. 5,057 plaice from off Mersey Estuary, 
January 1909; shrimp trawl-net ($-inch mesh). 



Mean length | Observed Calculated Constants. 
cms. frequency. | frequency. 
4-5 113 13-84 N =5057 
5:5 1168 1197-45 d=0-776943 
6-5 1487 1336-90 fg=3°514413 
75 920 949-71 &3= 10-875396 
Ati rere 601 575-27 Ha = 98-07792 
9-5 401 326-09 Bi =2-724768 
10-5 168 179-66 B= 7-940757 
11-5 80 98-15 k=2-024 
12-5 36 53-69 r=—14.81712 
13-5 30 29-59 qi= 18-82236 
14-5 16 16-44 qa= 200524 
15-5 16 9-29 a= 14-10833 
16-5 10 5:31 Log VY (qi)=15-56691 
17:5 u 3:07 Log T (qi—de— 1) = 11-8944 
18-5 1 1-80 Log TY (q2+1) =0-30919 
19-5 3 1-07 Mean =7-2'76943 
Mode =5:72974 
Log yo= 25:248629 
The ordinate at the mode is 1396-7. 
Fig. 3, p, 214, is the graph of the rough and the 
smoothed data. The latter are given in the above table. 
