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 



