CHAP. XI. 



BIVALVES: 

 DONAX; Wedge Shell. 



Q. WHAT information have you to give me 

 respecting the Donax? 



A. That shells of this genus have their mar- 

 gins often crenated, or crenulate (having blunt 

 teeth), with the frontal margin very obtuse. That 

 the hinge has two primary teeth and one mar- 

 ginal, and that the ligament is external. 



Q. Are there no other distinguishing charac- 

 teristics of this genus ? 



A. Yes. The shells are nearly all triangular, 

 inequilateral, concave on the anterior slope, and 

 assume the form of a wedge. They generally 

 gape a little at each end. 



Q. From what is the name Donax derived ? 



A. From a Greek word signifying an arrow. 

 The name is illustrative of the habits of this 

 curious shell-fish. It darts into the sand with the 

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