120 THE ELEMENTS 



Fig. 4th. Hinge of the Cardium 

 Aculeatuni* b Lateral tooth, dd mid- 

 dle teeth, // spines. 



Fig. 5th. Hinge of Mactra Hians. 



Fig. 6th. Inside of both valves of 

 the Donax Truncuhis, A Left valve, 

 B right valve, b lateral teeth, e pri- 

 mary complicated tooth, or cleft in 

 the middle, 7nm crenulated margin. 



Fig. 7th. Hinge of Venus Gallina. 

 a a Primary teeth, b lateral tooth. 



Fig. 8th. Hinge of Spondylus Gee- 

 deropus. ^'Incurved teeth. 



Fig. 9th. Hinge of Chama Cor. 



Fig. 10th. Hinge of Area Pilosa, 

 kk Numerous small teeth; the dis- 

 tinguishing characteristic of the ge- 

 nus Area. 



Fiff. 11th. Hinore of Ostrea Varia. 

 g Cavity of the hinge, h superior ear, 

 i inferior ear. 



Fig. 12th. Hinge of Anotnia 

 EpMppium. 



