SEA-FIS11ERIES LABORATORY. 477 



however, the stages of Waddington's Series A for the 

 first two years. 



First year. The larva was probably hatched in 

 June. During the first year the crab cast eight times, 

 and at the end of the first year (June to June) it was 

 30*75 mm. broad. 



Second Year. The crab cast twice (September and 

 March), and was 45*75 mm. broad at the end of its second 

 year. (In the first two years the ratio of increase varied 

 considerably. It will also continue to vary throughout 

 life, but for practical purposes I intend taking the ratio 

 of increase to be uniformly J, which is an average ratio.) 



Third year. There will probably be two castings, so 

 that at the end of the year the crab will be 70*6 mm. 

 broad. 



Fourth year. There will be only one ecdysis. At 

 the end of the year the crab will be 88 mm. broad. 



Fifth year. Only one casting. Size at the end of 

 the year, 110 mm. The crab will now be mature, and if 

 a female will probably be fertilised while in the " soft " 

 condition. 



Sixth year. The crab will not cast.* 



Seventh year. The crab will cast once, and will be 

 137*5 mm. in width after ecdysis. Fertilisation will 

 again be effected when the crab is " soft.*' 



Eighth year. The crab will not cast. 



Ninth year. The crab will cast, and after ecdysis 

 will be 171*8 mm. broad. Fertilisation will take place 

 immediately after ecdysis. 



I believe it to be highly probable that after the 

 female crab attains a size of six inches (150 mm.) ecdysis 

 will only take place once in three years (see below under 



* There is every reason to believe that after attaining maturity 

 the crabs only cast once in two years. 



