108 Part III. — Eighteenth Anmial Report 



Month 

 when Set 

 Free. 



Condition 

 of Shell on 

 Recapture. 



Intervals of Freedom — Days. 



July. 



S 



H 



H 



34. 

 ... 



86, 103. 



August. 



S 

 ii 

 H 



24, 26, 42, 49. 



54, 54, 60, 82, 83. 



59, 66, 70, 113, 119, 119, 129. 



September. 



S 



H 



H 



2, 2, 2, 2, 2, 3, 3, 5, 6, 11, 14, 16, 19, 21, 24. 

 23, 28, 31, 31, 33, 49, 54, 94. 

 38, 52, 59, 92, 115. 



October. 



S 



H 



H 



9, 16, 18, 20, 20, 22, 25, 29, 32, 52. 

 24, 37, 47, 83, 101*, 103. 

 61, 80, 103, 128, 177. 



November. 



S 

 ii 

 H 



9, 9, 11, 11, 12, 14, 18, 24, 26, 26, 27, 40, 40, 41, 42, 52. 



54, 63, 68, 74-. 



97, 165, 165, 165, 184. 



December. 



S 



H 



H 



10, 11, 30, 30. 

 16, 56. 



* The crab here referred to was captured after an interval of 86 days; after 15 days in confine- 

 ment, it was still not quite hard enough for market. 



The crab which was not completely hard after 101 days was set free 

 in October. All these crabs had been caught in the creels. We do not 

 know how soon after casting a crab leaves its retreat in search of food ; 

 but the primary calcification, which renders it capable of defending itself, 

 appears to ensue within a few days. While, then, the facts supplied by 

 the labelling experiment clo not entitle us to fix the limits of the period 

 of hardening, we have at least evidence of the time a crab may remain 

 soft, viz. 90 to 100 days. Since it is not improbable that the shell had 

 been about a week old when the crab was taken first of all, and since 

 another week would doubtless at least be required for complete harden- 

 ing, we get a period of 115 days, which is practically four months. The 

 conclusion, then, to be drawn from these data is that a crab which is 

 soft in October may require four months before it is legally hard. We 

 are unable to judge how far the season of the year in which casting 

 takes place operates in aiding or retarding the process of hardening. 

 One thing is certain, that the rapidity of recovery must be dependent 

 on the amount of food which the crab secures, and, as this necessarily 

 varies with the individual, there is reason to suppose that the length of 

 the period of softness is subject to considerable variation. Although 

 the evidence is very incomplete, I am of opinion that a crab which casts 

 in July will recover its hardness in a shorter time than the crab which 

 casts in September. 



In the case of the lobster Herrick* considers that six to eight weeks 

 are necessary for hardening to the condition of the old shell. Princef 



* Op. cit., p. 95. 



t Op. cit., p. 10. 



