THE CATTLAGE, AND HINGE TEETH. Ill 



PLATE XIV. 



The Cartilage, and its arrange- 

 ment; and The Hinge-Teeth. 



The cartilage of Scallop and Oyster shells is in the 

 form of a triangle, with the apex directed towards the 

 umbo. It is of a resilious nature, but when dry, 

 exceedingly hard and unyielding. It varies considerably 

 in shape, size, and the position it occupies. See also 

 descriptive labels in the plate. 



" The ' Ligament ' is a thin horny, inelastic band 

 connecting the hinge of each valve ; it is wedged within a 

 cleft in the Shell and is often more or less connected with 

 the ' Cartilage.' The * Cartilage ' is of a somewhat 

 similar substance, but is thick, compact and fibrous, and 

 occupies a 'pit.' Its action is to keep the valves open, in 

 opposition to the Adductors. It differs chemically from 

 the 'Ligament.' " 



Figs. 1, 1 A. Valves of Pecten. "In Pecten the 

 Ligament runs the whole way along the hinge-line, the 

 Cartilage being central. 



Figs. 2, 2A. Valves of Anomia. '' Cartilage carried 

 upon a process." 



Figs. 3, 3A. Valves of Ostrea. " In the Oyster there 

 are no Hinge-teeth." 



Figs. 4, 4A. Valves of Cardium. "Lateral teeth, 

 Cardinal teeth." 



Figs. 5, SA. Valves of Pholas. " In Pholas there is 

 no Cartilage." 



Figs. 6, GA. Valves of Tettina. " Cartilage- shelf 

 perpendicular." 



Figs. 7, 7 A. Valves of Solen. " Cartilage carried 

 upon a shelf." 



