On the 29th May, 1909, and again on the 21st October of 

 the same year, the shell was cast, but there were no eggs 

 during the whole of this year. 



In 1910 the shell was cast on the 27th May, and again on 

 the nth August. On the 25th of the same month copulation 

 was observed with a male, ^and on the 26th the female was 

 observed to be carrying eggs. These were of a pale whitish 

 colour, but in a few days acquired a yellowish tmge. About 

 the beginning of October the eggs were cast off from the 

 abdominal appendages, and by the 8th only a few were left. 

 On the 8th July, 1911, the shell was again cast. 

 Female B shed eggs about the middle of October, 1906, 

 cast shell i6th April, 1907, and was carrying eggs some time 

 before the 2nd June (the first of the four to have eggs again). 

 It cast its shell again on the 26th October with the eggs still 

 attached, an entirely abnormal occurrence. On the 9th June, 

 1908, the shell was again cast. The animal died on the 20th. 

 Female C shed eggs about the middle of October, 1906, 

 cast shell 28th April, 1907, had eggs about 15th June, 1907, 

 and shed eggs 25th October, 1907 ; cast shell 2nd June, 1908, 

 and had eggs shortly afterwards. Cast shell 7th June, 1909, 

 but had no eggs that year. Cast shell 3rd June, 1910, and 

 had eggs shortly afterwards, being attended by male some 

 days before. On 19th June, 19 10, cast sheU. 



Female D shed eggs about middle of October, 1906, cast 

 shell 7th June, 1907, attended by male 22nd June, 1907, and 

 had eggs on the 24th. By the 25th October all eggs were 

 shed. On the 26th May, 1908, cast shell, and had eggs. On 

 the 29th June, 1909, cast shell, and had no eggs this year. 



In drawing any conclusions from these experiments allow- 

 ance must of course be made for the more or less unnatural 

 conditions under which the animals h\'ed (in the confined space 

 of the aquarium tanks). That this had some influence, 

 though the animals themselves were apparently quite normal, 

 is shown by the fact that in all but the first year the ova did 

 not develop normally and no larvse hatched out. 



Several important conclusions may, however, be drawn— for 

 instance, that the females cast their shell about mid-winter, 

 that soon after casting their shell and while still soft they are 

 fertihsed by the male and almost at once extrude the eggs, 

 which are carried externally for about five months. The date 

 of the casting of the shell in the females may therefore be taken 

 as at the beginning of the spawning time. 



The dates of the casting of the shell in the case of the four 

 individuals are shown more clearh^ in the following table :— 

 [C.P; 5-'i3-] 



