ON CRUSTACEA. 
297 
works on the history of fishes, or that of insects, in which a 
particular chapter has not been devoted to it, from Aristotle, 
who was the first to treat of it, down to the present day. 
There are threads attached to the tail of both sexes, varying 
in number and figure, and mobile at the base. To these 
threads the female fixes her eggs, and it is probable that those 
of the male may serve some purpose in the act of generation ; 
but as the coupling of the astaci has not been yet observed, 
nothing positive is ascertained respecting this subject. 
It is with the claws that these astaci catch their prey ; they 
also employ them as a weapon of defence, as may easily be 
proved by presenting any thing to them, when they are in the 
water. The animal grasps with so much force, that to make 
it let go it is necessary to break the foot or burn the tail. 
Aremarkable peculiarity in the feet of the astaci of both sexes 
is, that they are the seat of the organs of generation. Buster, on 
the authority of another observer, reports thus concerning the 
sexual intercourse of these animals : — When the male attacks 
the female, she throws herself backwards, and then they em- 
brace closely by means of the feet and tail. After this, at the 
end of two months, the female is found charged with eggs. 
The astaci lay a great number, which, as I have before ob- 
served, they have the art of attaching to the mobile threads 
underneath their tail, and which they constantly carry there, 
until the little ones are disclosed. There is some reason to 
believe that these eggs grow and augment in volume, while 
they are thus attached to those threads. They are enclosed 
in a species of sac, which is a continuation of their membra- 
naceous pedicle : each thread, thus charged, represents a 
bunch of grapes, the more exactly too, as the colour of these 
eggs is of a reddish brown. 
When the young astaci are disclosed, they are transparent and 
extremely soft, but in all other respects similar to the old ones. 
As their delicacy would expose them the first days after their 
