COUNCIL — JULY 1905 — APPEND. C 50 
belong more properly to the work of the separate countries and need not be con- 
sidered here. The Bureau takes it for granted, that each country makes its material 
as representative as possible in these regards before sending it in. 
A second difficulty of a general nature, that is, concerning the material as 
a whole, is the 
Conversion of lengths into weights: The object of the present invest- 
igation is to determine the quantities, by weight or number, of the small plaice 
under any given size landed from the different regions of the international area. 
The statistical data published in the various countries concerned give the weight 
of the plaice (except for a portion of the plaice landed in Denmark, which is 
given in scores). The measurements of plaice sent in to the Bureau give the 
lengths of the fish measured. As is well-known, the percentages by length do 
not quite agree with the percentages by weight in a collection of fishes of 
different lengths. Consequently, the measurements of lengths sent in have had to 
be converted into weights, before it was possible to estimate the proportions of 
the small plaice: under any given size which entered into the total quantities of 
plaice landed in the various countries. 
To enable the conversion of lengths into weights to be made, a conside- 
rable amount of material was present from all the countries concerned except 
Germany. The English material gave the average weights of all fish measured at 
each size, the Dutch and the Danish only the average weights of samples. In the 
case of Denmark, however, other material was also obtainable from Dr. A.C. 
JoHansen’s work on the plaice, showing the average weight of a number of speci- 
mens at each size length. In the case of Holland, the average size of each sample 
was compared with the average weight and a scale was thus formed for the 
smaller plaice. The larger sizes, however, were not well-represented in the Dutch 
material and the average weights for each size over 27 cm. have consequently been 
estimated by comparison with the English and Scottish data. The Scottish data 
are given by Dr. T. W. Furron in the XXIII. Report Fishery Board for Scotland 
for 1903, but only concern every fifth centimeter. The scale used for the German 
measurements was the Danish, as the fishing-grounds of these countries, so far as 
the small plaice are concerned, are very much the same. 
The various data, when tabulated and compared as in Table IV, show a 
very apparent disagreement. The Dutch and the English agree fairly well, both 
