ISO CRUSTACEANS. 



was gone, and paleness announcing the arrival of maturity, Plate XLIII. 

 fig. 1. Numerous young having burst their capsules, were at this time 

 seen in the vessel, and they were hourly augmenting. 



These creatures appeared of light grey colour, with black eyes, a large 

 body, a dorsal spine, and a long tail. A yellow substance occupied the 

 body, perhaps some residuum ; or the shell might be stained by colouring 

 matter. At this early stage they sprung through the water. 



A multitude of young continued escaping from the capsules, until 

 the whole were discharged ; and on the thirteenth of the month, the 

 animal had recovered its symmetrical proportion. 



Thus the roe was dispersed in about a fortnight. 



Within three weeks from the first appearance of the young, while 

 examining different living animals in the same vessel containing the 

 subject of these observations, I was again betrayed into such an error 

 as detailed in the outset of this section. Exuviation had unexpectedly 

 taken place, and I was once more surprised as by the sight of a stranger 

 animal, Plate XLIII. fig. 2 ; The new shell was much clearer and much 

 purer than the old ; the light portion on each side of the dark stripe 

 extending to the margin, more vivid than previously. This shell 

 was not sensibly larger than before, but the colour infinitely finer. 



It will be observed that this specimen had borne an ovarium, which 

 was exhausted before exuviation. In as far as I have been able to dis- 

 cover, such an important change never takes place under other condi- 

 tions, but the proximity of the two incidents are unknown : they are 

 never cotemporary. As the whole integuments separate without the 

 smallest reserve, it is plain that exuviation preceding an exhausted 

 ovarium, might entail destruction on the brood, whereas indemnity at- 

 tends its postponement. 



A small female mutilated of all but three of the legs, had been in 

 my possession two months. In the middle of November, the roe, bright 

 scarlet, was now approaching fast to maturity. I was anxious to pre- 

 serve the animal for the result of exuviation, and to ascertain whether 

 this event would precede dispersion of roe. Spite of so great a mu- 

 tilation, it seemed to feed, but it had been so severely wounded, that it 



