THE FRESH- WATER MUSSEL. 



113 



teeth, of their shell into the deck (Fig. 106). While 

 they are thus carried about by this water perambulator, 

 they pass through many changes, and at last become 

 exactly like their parents ; then they leave the tail of 

 the fish, and settle down in the mud for the rest of their 



Fig. 106. 



Young Mussel traveling on the Tail of a Frsn. 



lives. The mussel is the most ambitious of all the ani- 

 mals we have yet examined ; he makes an attempt to 

 keep a servant for each kind of work, and he succeeds 

 pretty well. As you have seen, he has muscles, blood- 

 vessels, NERVES, EARS, HEART, MOUTH, GULLET, STOMACH, 



intestines, liver, and kidneys. He lacks only a few 

 things, such as head, eyes, teeth, backbone, etc., to lift 

 him into a still higher class. All this we have learned 

 about a little creature which looks at first sight like a 

 mere bit of slimy flesh. The house itself is a very 

 pretty piece of architecture ; I hardly know what style 

 to call it. Its arches suggest the " early Roman." It 

 is sometimes called the skeleton — you remember the 

 leaf of the bean had a skeleton ; but the soft parts of 

 the leaf lie between and over the parts of the skeleton. 

 The mussel's or anodon's skeleton lies outside its body, 



