Exuviation in Shrimps and Lobsters. 173 
I have little doubt that if the creature had lived but a few days 
longer, the separation would have been complete, and the animal 
would have escaped from its prison. 
The growth of the young of the long-tailed Crustaceans, is well 
known to be exceedingly rapid ; and there seems reason to believe 
that the process of exuviation is repeated at least two or three times 
in the course' of the first year of their age. In the course of 
a summer, among many prawns one or two may always be found in 
a state that indicates the having lately passed through this process ; 
but about October or November they all seem to undergo it at once, 
the breeding season finishes, and no further change in the shell takes 
place until the approach of the spring. It is not improbable that 
the general opinion is correct, which limits the exuviation of the 
adult animals to once in the year ; but from the marks of old inju- 
ries, and the incrustation of parasitic animals, I have come to the 
conclusion that in advanced age the lobster does not throw off its case 
with any regularity, and perhaps not at all. 
