OTHEK CRUSTACEA. 39 



The hermit crab backs into the empty shell of a sea- 

 snail, thus protecting the soft hinder parts of his body, 

 and with his head and anterior appendages projecting, 

 crawls about, dragging his house with him. When the 

 hermit outgrows his shell, he exchanges it for a larger 

 one. When first hatched it is like other crabs. 



The sand crab runs rapidly on the beach, and when 

 pursued, and not near its hole, quickly buries itself in the 

 sand, leaving only the black tips of its eyes exposed. This 

 crab is nearly white. 



The fiddler crab is small. The male has one large claw, 

 which it holds across the front of its body. The other 

 claw is very small, the two suggesting the violin and 

 bow. It lives in holes between high and low tide 

 marks. The writer has seen these crabs covering the 

 beach for many rods, so thickly crowded as almost to 

 touch each other, making a loud rustling noise as they 

 shuffled away from their uninvited visitor. 



Lobsters, crabs, and shrimps live in salt water. 



Some small crustaceans, found in ponds, swim actively 

 about, enclosed in a bivalve shell, formed by the growth 

 of the carapace, which they can open and shut. 



Collect a variety of the common small crustaceans, keep 

 them in a fruit jar, and study their habits. 



Consult " Worms and Crustacea " in Hyatt's " Guides 

 for Science Teaching," " Packard's Zoology," and Huxley's 

 "Anatomy of Invertebrated Animals." 



Look over the descriptions of the crayfish and sow-bug, 

 and make a list of the characters common to the two. Let 

 this list represent the characters of Crustacea generally. 

 Place side by side (1) the list of characters common to all 



