Animals. 87 



Alice. The outside is round. 



Henry. There is a point (beak) on the outside. 



John. The edge is full of fine notches. 



Isabel. There is a dark purple mark on the inside. 



Hattie. There are two shining spots on the inside near 

 each end. 



Alice. One side is sharp like a knife. 



Willie. There are three little sharp teeth on the inside 

 near the point (beak). 



Charlie. There is a line near the edge running all around 

 the shell. 



Harry. The line has an angle near one end of the shell. 



Teacher. That is what I have in mind. The lines on 

 the outside are called lines of growth, because as the clam 

 grew his shell grew little by little. The point on the out- 

 side is called the beak or umbo. It is the beginning or old- 

 est part of the shell. The fine notches around the edge 

 help the clam to hold the shell firmly together when it is 

 shut. Some shells have but little of the purple on them, 

 and some are very beautifully colored. The two shining 

 spots inside are where the strong muscles are attached to 

 help the clam to pull his shells together and hold them shut. 

 The sharp knifelike edge on the back is called the hinge, 

 because it fits into a groove on the other shell (valve). The 

 three teeth are to fit into three little sockets on the other 

 valve so as to hold both shells firmly together. Do you see 

 how safe the clam is when his shell is shut ? 



The clam cannot leave his shell. He grows to it. He 

 has a loose cloak or mantle that covers him and grows to 

 the inside of the shell down to the line that runs all around 

 near the edge. The mantle rolls up behind and does not 

 grow so near to the edge, and that makes the notch on the 

 back. We call the part of the cloak that is rolled up the 

 siphon and the notch on the shell a sinus. The word sinus 

 means a bay, and this is so called because it looks like a bay 

 on the map. The siphon is important, for it helps the clam 

 to eat and breathe. 



