20 THE ELEMENTS 



Fig. 4th. Hinge of the Cardium 

 Aculeatum. b Lateral tooth, dd mid- 

 dle teeth, // spines. 



Fig. 5th. Hinge of Mactra Hians. 



Fig. 6th. Inside of both valves of 

 the Donax Trunculus. A Left valve, 

 22 right valve, b lateral teeth, e pri- 

 mary complicated tooth, or cleft in 

 the middle, mm crenulated margin. 



Fig. 7th. Hinge of Venus Gallina* 

 a a Primary teeth, b lateral tooth. 



Fig. 8th. Hinge of Spondylus Gee- 

 deropus. ff Incurved teeth. 



Fior. 9th. Hinge f Chama Cor. 



Fig. 10th. Hinge of Area Pilosa. 

 kk Numerous small teeth; the dis- 

 tinguishing characteristic of the ge- 

 nus Area. 



Fi«r. Hth. Hinge of Ostrea Varia. 

 g Cavity of the hinge, h superior ear, 

 • inferior ear. 



Fig. 12th. Hinge of Anomia 

 Ephippium. 



