44 CONCHIFERA, SHELL-BEARERS. 



CHAPTER VII. 



Eleventh Class. — Conchifera. 



Two Orders. — 1st. Bimusculosai two muscular 



impressions. 

 2nd. Unimusculosa^ one muscular impression. 



"This class/' observed Mr. Elliot, "contains 

 all the bivalves of Linnaeus, and some genera 

 taken from the univalves and multivalves. 



" The animals of this class are shell-hearers or 

 carriers^ they remain constantly fixed in their 

 habitations : the body is fastened to the shell by 

 one or two strong muscles: when the shell is 

 vacant we find the cicatrix. Refer to your 

 explanation of terms, and you will find the 

 word. 



" The body is soft, without joints, without head 

 or eyes ; it is wrapped in a mantle or tunic. The 

 mouth, always hidden in the tunic, is merely an 

 opening to admit food, without jaws or teeth. 

 The shell is always bivalve ; the valves united 



