of the Fishery Board for Scotland. 



107 



Officer, Peterhead, to the effect that the female casts yearly in J uly, 

 August, and September. 



The question as to how long an interval elapses between casting and 

 the complete hardening of the new shell is of considerable importance. 

 As has been mentioned, the legal test of hardness is the impossibility of 

 pushing the thumb through the shell. There is, so far as I am aware, 

 only one recorded case of a crab which had been kept in confinement 

 from the moment of casting until it was completely hard. This crab, 

 which MeekJ mentions, cast on August 12th, and was found at the end 

 of December to be hard; " thus four to five months are necessary for 

 the hardening process." This specimen was kept in a "hullie " by 'Mr. 

 Douglas, Beadnell. While it is very probable indeed that confinement 

 will retard the process, still, from a certain amount of indirect evidence 

 which is supplied through the labelling experiments at Dunbar, the 

 above-mentioned interval would appear to be not very much in excess 

 of the period required by some of the crabs at least. The Dunbar 

 labelling experiments were carried out in the first instance with a view 

 to testing the summer and autumn migrations of the crab. For this 

 purpose a large number of soft crabs — 999 in all — were labelled and set 

 free in the months of July, August, September, October, November, and 

 December ; of these, about 1 1 per cent, were recovered after various 

 intervals of freedom. On recapture, the condition of the shell of the 

 crab, in addition to other characters, was carefully noted. In Tables X. 

 and XI., the particulars referring to the condition when set free, the 

 interval of freedom, the condition on recapture of each crab, are given in 

 detail. In some cases also the sex and size of the crab are recorded. The 

 crabs^of each lot, although designated soft, were not all in the same stage 

 of hardening ; in other words, they had not cast their shells at the same 

 time. While some of them were so soft and clean that they had 

 doubtless cast within the previous few days, the shells of others had 

 already undergone a considerable amount of calcification. Thus it 

 happens that certain of the crabs were found to have become quite hard 

 after an interval of 60 days (in one case after only 38 days), while six 

 others were found to be still soft at the end of 74, 82, 83, 83, 94, and 

 100 days of freedom respectively. The latter crabs, while they were 

 almost completely hard and would possibly have passed as marketable, 

 could still have been broken over the gill cavity. In testing a crab of 

 this stage, there is a considerable risk of lacerating the thumb on the 

 sharp edges of the broken shell. The following Table shows the month 

 in which the soft crabs were labelled, the time of freedom, and their 

 condition when recaptured. The crab when it has almost completely 

 recovered its hard condition is marked h, while the soft crab is 

 represented by S, and the legally-hard crab by H. 



* Op. cit. 



f Op. cit., p. 12. 



X Northumberland Sea Fisheries Committee, 1898, "Report on the Trawling Excr 

 sions," Newcastle-on-Tyne, 1898, p. 28. 



G 



