33 



season, the ova are in an undeveloped condition and remain in 

 this state practically during the period of hardenmg, a period of 

 some months. The crab therefore cannot spa^vn at the next 

 spawning season, that is to say, about the end of the year. It is 

 postponed until the spawning season of the following year, a period 

 of some fifteen months after the ecdysis at which pairing occurred. 

 In consequence of this hatching will take place in the summer of 

 the second year, and casting immediately thereafter ; thus at 

 the end of a period of about two years. It was tempting to say 

 without the material we are now considering that in this case 

 growth had to wait on reproduction, but it is evident that at the 

 stage of first maturity growth is in adjustment with the needs of 

 maturity. 



There is proof likewise from our marking experiments that 

 a female crab after an ecdysis may remain for a period of over tw^o 

 years before spawning, vide Report (new series IV., p. 40) for an 

 account of a specimen returned from Dunbar, measuring 15-2 cm. 

 Similarly in the Report (new series V., p. 7) the record is given 

 of a female which after an absence of three years and five months 

 w^as in March berried. This specimen measured 18 cm. We 

 have the proof therefore that spawning may be postponed over 

 the periods demanded by the chart. It may be said that w^e have 

 no proof that in these cases spawning may not have taken place, 

 that during this period of years there may have been two spawn- 

 ings. This is a possibility which must not be overlooked. In 

 the case of, let us say, a female casting at seven years old spawning 

 could take place about January, after she attains eight years, and 

 again about January after she is nine years. Williamson offers 

 some considerations to indicate that such an event takes place. 

 He has shown, for example, that the spermathecae are not 

 entirely emptied of their contents in the berried female, and 

 that a second lot of ova could be fertilised after the first had 

 been hatched. That this takes place sometimes even if rarely is 

 of considerable interest for it indicates that the periodicity of 

 reproduction tends to be maintained. 



On the other hand we have evidence to show that it is not 

 common, that as a rule spawning only takes place once during 

 the instar. In the Report (new series III., p. 74) referring to 

 the results of marking experiments it was pointed out that in 



