Other Invertebrate-Animal Study 469 



up the soil which they excavate around the mouth of the well, making 

 well-curbs of mud ; these are ordinarily called "crawfish chimnies." The 

 crayfishes find their food in the flotsam and jetsam of the pool. They 

 seem fond of the flesh of dead fishes and are often trapped by its use as 

 bait. 



The growth of the crayfish is like that of insects; as its outer covering 

 is a hard skeleton that will not stretch, it is shed as often as necessary; it 

 breaks open down the middle of the back of the carapace, and the soft, 

 bodied creature pulls itself out, even to the last one of its claws. While its 

 new skin is yet elastic, it stretches to its, utmost; but this skin also 

 hardens after a time and is, in its turn, shed. Woe to the crayfish caught 

 in this helpless, soft condition after molting! For it then has no way to 

 protect itself. We sometimes find the old skin floating, perfect in every 

 detail, and so transparent that it seems the ghost of a crayfish. 



Not only is the crayfish armed in the beginning with a great number ofr 

 legs, antennas, etc., but if it happens to lose any of these organs, they will 

 grow again. It is said that, when attacked, it can voluntarily throw off 

 one or more of its legs. We have often found one of these creatures with 

 one of the front claws much larger than the other; it had probably lost 

 its big claw in a fight, and the new growth was not yet completed. 



I have been greatly entertained by watching a female crayfish make 

 her nest in my aquarium which has, for her comfort, a bottom of three 

 inches of clean gravel. She always commences at one side by thrusting 

 down her antennae and nippers between the glass and stones; she seizes a 

 pebble in each claw and pulls it up and in this way starts her excavation; 

 but when she gets ready to carry off her load, she comes to the task with 

 her tail tucked under her body, as a lady tucks up her skirts when she has 

 something to do that requires freedom of movement. Then with her 

 great nippers and the two pairs of walking feet, also armed with nippers, 

 she loads up as much as she can carry between her great claws and her 

 breast. She keeps her load from overflowing by holding it down with her 

 first pair of jaw-feet, just as I have seen a schoolboy use his chin, when 

 carrying a too large load of books ; and she keeps the load from falling out 

 by supporting it from beneath with her first pair of walking legs. Thus, 

 she starts off with her "apron" full, walking on three pairs of feet, until 

 she gets to the dumping place; then she suddenly lets go and at the same 

 time her tail straightens out with a gesture which says plainly, "There!" 

 Sometimes when she gets a very large load, she uses her second pair of 

 walking legs to hold up the burden, and crawls off successfully, if not with 

 ease, on two pairs of legs, a most unnatural quadruped. 



I had two crayfishes in a cage in an aquarium, and each made a nest in 

 the gravel at opposite ends of the cage, heaping up the debris into a parti- 

 tion between them. I gave one an earthworm, which she promptly 

 seized with her nippers; she then took up a good sized pebble in the nip- 

 pers of her front pair of walking legs, glided over to the other nest, spite- 

 fully threw down both worm and pebble on top of her fellow prisoner, and 

 then sped homeward. Her victim responded to the act by rising up and 

 expressing perfectly, in his attitude and the gestures of his great claws, 

 the most eloquent of crayfish profanity. In watching crayfishes carry 

 pebbles, I have been astonished to see how constantly the larger pair of 

 jaw-feet are used to help pick up and carry the loads. 



