43 



probably the time of casting and pairing in the case of the females. 

 The males cast usually in Februan^ March and April. 



The tables which Storrow prepared of the measurements of 

 large numbers each month show on analysis sizes which stand 

 out prominently. These have been taken to represent stages 

 in growth. The results of the analysis are given in the following 

 table, which may be taken as a tentative attempt to indicate the 

 growth of this species. 



TABLE X— :N^0RWAY LOBSTER. 



The population of males centre about 16 cm., and of the 

 females about 12 cm., and they are then apparently about four 

 years old. It is about this period also that maturity may be 

 said to be reached in the average condition. 



The foregoing examples show that the Decapoda have a 

 long period of development and growth. Maturity is not reached 

 in some of them until they are five years old, and life may be 

 prolonged for many years afterwards. It will be apparent, for 

 example, that a lobster of say 12 ins. (30-5 cm.) is about ten j^ears, 

 and of about 16 ins. (40 cm.) at least about fifteen years old: one 

 was caught at Marske-on-Sea which measured 29 ins. and weighed 

 15J lbs. Crabs also may be reckoned to reach as great an age. 

 A male crab was found in June this year (1918) to measure 23*2 

 cm. (9 ins.) across the carapace and to weigh 2,500 gr. (5*5 lbs.) 

 A crab caught at Brixham, now in the Hull Museum, weighed 

 12 lbs. Such large examples cannot be less than twenty years old. 



In complete contrast to the Decapoda and the Stomatopoda 

 the lower Malacostraca and the Entomostraca grow to full size 

 in a short period of time. Some have an annual phase, and others 

 produce several broods in the year, all of which may become 

 mature in the one season. 



