SEA-FISHERIES LABORATORY. 103 



and troublesome when the subsequent tabulation of the 

 measurements is made. All the figures given are mean 

 lengths. The fish is laid on the measuring board and the 

 division in which its tail falls is noted. All fish between 

 n and ?i + 1 cms. are recorded as n cms. The mean length 

 is then n + 0'b cms. On board the " James Fletcher" a 

 brass pin is stuck into the measuring board opposite the 

 tail of the fish. The number of pins in each cm. division 

 is then read off. This method is the most accurate of 

 all those employed. In most cases the sample of plaice 

 sent to me for further examination has already been 

 measured on board the " James Fletcher." On receipt 

 it is re-measured and I give in the Table on p. 184 the 

 results of four of such duplicate measurements. It will 

 be seen that in two cases the numbers are practically 

 identical. In the other two cases there is a discrepancy 

 which is to be expected, and which is due to contraction 

 of the fish after death. Why it is that this discrepancy 

 is not always apparent I do not know. Possibly a fish 

 contracts when rigor mortis sets in, and relaxes again 

 when this passes off. In the two cases where this dis- 

 crepancy occurs the mean difference is 0'58 cm., that is 

 the fish when measured by Captain Wignall's men were 

 about \ cm. longer than when I measured them. 



All the measurements recorded in the Tables on 

 pp. 153 to 171, were made on living fish.. The first thing 

 done, when the trawl net is cleared, is to measure and 

 record the plaice and soles. The numbers are then entered 

 on the log sheets. Sometimes the entire catch is sent to 

 the Laboratory, but more usually only a part is sent. 

 These samples are examined for length and weight, so as 

 to get average weights and values of the coefficient k; 

 for age, by inspection of the otoliths; for maturity, by 

 examination of the gonads; and occasionally for food 



