482 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



As already slated, mature crabs generally east from 

 August to November, and immediately before and after 

 ecdysis their flesh is ,k watery " and lias a bitter taste, and 

 is, therefore, unfit for food. The above symptoms are 



also characteristic of the " granny " crab. 



" Grannies " are found only amongst females above 

 six inches in breadth. The explanation of this is that 

 those females below this size dc not retain their shells 

 long enough for the latter to acquire the discoloured and 

 broken appearance. An interval of two years between 

 successive castings is evidently insufficient to produce this 

 effect. 



This diminution in the frequency of casting in the 

 females above six inches may be due to the general rule 

 that as the crab grows older the period between successive 

 castings tends to become longer until a time is reached 

 when ecdysis ceases altogether. But this explanation 

 does not appear to be sufficient to account for the supposed 

 difference between males and females in this respect. An 

 important factor in determining the time of casting is the 

 condition of the reproductive organs. Ecdysis will not 

 take place in the female so long as there is a supply of 

 spermatozoa in the spermathecae. The supply of 

 spermatozoa received by the soft female is generally 

 sufficient to fertilise at least two batches of eggs in 

 successive winters, and it is highly probable that the 

 older crabs will spawn three times between each moult. 

 Williamson has emphasised this point, and has also stated 

 that the soft female which, for any reason, does not 

 become fertilised, will cast in the following summer. 

 The frequency of ecdysis, then, in mature females is 

 influenced by the condition of the spermathecae, and it is 

 probable that on this account the older females will east 

 less frequently than the younger ones. 



