CHAPTER X. 

 THE LOBSTER AND OTHER CRUSTACEANS. 



THE lobster is so large an animal, so easily procured and 

 examined, that its study affords material for a series of ex- 

 cellent object-lessons for young students. Boiled lobsters, 

 which can be purchased for a few cents apiece in our sea- 

 board towns, are as good for our present purpose as living 

 or alcoholic specimens. If the student lives inland, espe- 

 cially in the Central and Southern States, a large crayfish 

 will answer the purpose equally well as the lobster. 



The lobster lives from below low- water mark to the depth 

 of from 50 to 100 feet, on a rocky bottom., where it hides 

 under rocks, its long antennae extended out of its retreat. 

 If disturbed when walking about over the bottom on its 

 sprawling legs, it will suddenly bend its tail under its body, 

 thus shooting backwards several feet. Its food is fish and 

 other animals, and it is also a scavenger. In life it is dark- 

 green, with some reddish tints ; when boiled it turns a 

 bright brick-red. 



We will now draw the pupil's attention to the more ob- 

 vious points in the appearance and external structure of 

 the lobster, and the student should have a specimen for 

 dissection. 



In the first place, notice that there is a well-marked head, 

 with feelers and eyes, as well as a hinder end, or tail ; there 

 are also an upper and an under side. Moreover, if an imagi- 

 nary line be drawn along the middle of the back from head 

 to tail, it will divide the lobster into two equal halves. To 

 use two rather long words, the lobster is bilaterally sym- 

 metrical, each half exactly repeating the other. 



The body is protected by a solid crust, formed mostly of 



