NEWLY-HATCHED CRAYFISHES. 43 



fringed, and is continued by longer or shorter thread-like 

 pedicles into the coat of the same material which invests 

 each egg. It very soon hardens, and then becomes very 

 firm and elastic. 



When the young crayfish is ready to be hatched, the egg 

 case splits into two moieties, which remain attached, like a 

 pair of watch glasses, to the free end of the pedicle of the 

 egg (fig. 8, A ; ec). The young animal, though very similar 

 to the parent, does not quite "resemble it in all respects," 

 as Roesel says. For not only are the first and the last 

 pairs of abdominal limbs wanting, while the telson is very 

 different from that of the adult ; but the ends of the great 

 chelae are sharply pointed and bent down into abruptly in- 

 curved hooks, which overlap when the chelae are shut (fig. 8, 

 B). Hence, when the chel£e have closed upon anything soft 

 enough to allow of the imbedding of these hooks, it is 

 very difficult, if not impossible, to open them again. 



Immediately the young are set free, they must instinc- 

 tively bury the ends of their forceps in the hardened 

 egg-glue which is smeared over the swimmerets, for they 

 are all found to be holding on in this manner. They 

 exhibit very little movement, and they bear rough 

 shaking or handling without becoming detached ; in 

 consequence, I suppose, of the interlocking of the hooked 

 ends of the chelae imbedded in the egg-glue. 



Even after the female has been plunged into alcohol, 

 the young remain attached. I have had a female, with 

 young affixed in this manner, under observation for five 



