296 ANIMAL SKETCHES. CHAP. 



only one-third of an inch long. But it is interesting, at 

 least to a zoologist. 



The eggs are laid in the autumn, and attached by a 

 viscid gluey substance to the swimmerets of the mother. 

 Not till the spring are the baby crayfish hatched. They 

 are curious, round-backed little fellows, which resemble 

 the adult in general appearance, but are somewhat differ- 

 ently proportioned. The tail, too, differs in having a 

 simple flap at the end, the broad lateral appendages not 

 having yet been set free from a wrappage of the outside 

 skin. The tips of the claws are curiously hooked ; and no 

 sooner is the little fellow hatched than he buries the 

 hooked points in the gluey substance by which the egg- 

 shell still remains attached to the swimmeret. When 

 once he has thus got a firm grip it is very difficult to 

 shake him off The reason for the development of this 

 curious habit is to prevent the helpless youngster being 

 carried away by the force of the current, and thus perhaps 

 out to sea to perish in the salt water. 



To the zoologist one interesting point about the baby 

 crayfish is that it is hatched in such a highly developed 

 condition. In many of the marine allies of the crayfish 

 the young are set free to lead an independent existence 

 when they are exceedingly minute, and when they are so 

 different in appearance that no one but a naturalist would 

 dream that they were baby crustaceans. They, in fact, 

 undergo a metamorphosis analogous to and not less 

 wonderful than that which an insect passes through in its 

 life-stages, from the egg through the caterpillar and chrysalis 

 to the perfect butterfly, moth, or beetle. But if in the case 

 of the crayfish the young were hatched in their minute 

 free-swimming independent condition they would be swept 

 downward by the flow of the current. They would thus 

 come to maturity, live and die some miles further down 



