230 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Fig. 1 is constructed from the data of Table II. The 

 percentages plotted are calculated on the whole sample, and 

 these figures may be necessary for a detailed consideration 

 of the life-history of the shrimp in local waters. I do not 

 consider it further in the meantime. It will be obvious, 

 however, that the variation in the percentage of berried 

 females in the whole catch may not give us accurate information 

 as to the period of maximum spawning, for it is based on the 

 males and females. We have, therefore, to calculate the 

 percentage of females that carry eggs and regard this (pro- 

 visionally) as giving information as to the period of the year 

 during which spawning is in progress. 



The data of 1913 and 1914 have therefore been combined, 

 and some additional samples obtained in 1912 and 1915 are 

 also included. The average percentages of female shrimps 

 carrying abdominal eggs (berried females) have been calculated 

 for each month. These new average percentages are as 

 follows : — 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



3-2 



23-4 



66-3 



62-7 



70-7 



68-9 



74-9 



69-0 



73-4 



41-9 



33-7 



7-6 





These figures are represented by 1 



the following graph : — 



So. 



Percentage 

 of females 





70- 



Carry inQ y' 

 abdominal / 







S-+ | 







ova 



















6o- 





















so- 





/ 















\ 



4o- 





/ 















A 





3CM 



J 



















X 





2o- 





T 



















\ 



\ 



IO - 



j\ 



/ 





















\ 



a 







r*-\ 





21 



Mon 



III 



Ths 



I 



J7 



m ' 



'if 



¥ ' 



U ' 



jm 



m 



IK 



I 'xr 1 



Fig. 2. Variation in the percentage of female shrimps carrying abdominal 

 during the years 1912-1915. 



