The Crayfish. 43 



LESSONS ON ANIMALS. 



FISHES. 



The Crayfish. 



Shortly after ice breaks up in early spring go to some 

 pond or stream with a dip-net made of thin cloth fastened 

 to a wire hoop. A little effort will secure a liberal supply 

 of larvae of frogs and other creatures. Crayfish will nearly 

 always be found, and usually there will be seen numerous 

 eggs fastened to the swimmerets under the long abdomen. 

 Place your material in a large shallow tin pan of water and 

 take to school. Here the complete change from egg to 

 crayfish may be observed by the children. It is interesting 

 if each child can have a bowl of water of his own to 

 observe, but I have found one large vessel of water quite 

 sufficient for observations of an entire room. If you fail of 

 securing eggs, you can at least have observations made 

 upon the adult. These observations should at least bring 

 out the following facts : i. Its body is jointed. 2. It has 

 ten jointed legs. 3. It has long antennae. 4. Its eyes are 

 on stalks, like those of the snail. 5. It can move either 

 forward or backward, but it prefers a backward motion. 

 6. In moving it turns the tail under and darts quickly 

 backward. 7. It uses the tail for swimming. 8. The jaws 

 move from side to side. 9. The first pair of feet is enlarged 

 into huge claws. 10. The body is covered with limy scales 

 (crusts). ii. Under the large side-plates are the gills. 

 12. The cray-fishes shed their scales (moult) from time to 



