( 24 ) 



2 strong teeth on each 

 valve. 



5. Plicatula. Lam. M. 



Inequivalved, narrowed 

 at the base, upper edge 

 rounded, sub - folded ; 

 beaks unequal, without 

 external furrows. Fig. 76. 



6. Spoi\dylus. Lin. M. 



Inequivalved, adherent, 4 strong cardinal 



auricular, with thorns or teeth on each valve ; an 



rugged ; beaks unequal ; intermediate hollow 



inferior valve with an ex- communicating at the 



ternal cardinal area or base with the external 



heel, flattened and divided furrow, 

 by a furrow, and enlar- 

 ging with age. Fig. 77. 



Ligament interior, re- 

 ceived in a cardinal hol- 

 low, between the teeth. 



Ligament interior, its 

 remains seen in the fur- 

 row without. (2) 



7. Podopsis. Lam. Foss. 



Inequivalved, sub-regu- 

 lar, adhering by its infe- 

 rior beak; the inferior 

 valve the largest and most 

 convex, and its beak 

 more advanced. Fig. 81. 



Hinge without teeth. 



Ligament interior. (3) 



8. Hippopodium. Sower- 

 by. Foss. 



Equivalved ; valves sub- 

 bilobed: a heart-shaped 

 cavity behind each beak. 



Fig. 



83. 



1 rugged tooth. 



Ligament exterior. (4) 



Oolite, at Grignon, Parnes, Bourdcaux, Doue, Bailleul, Mont-Marlus, Turin, 

 Venice, Fcrte-Benard, Perpignan, Mans, Coulaines, Dtcize, Cliauffour, Boutonnet, 

 Sienna, Marsigni. 



(1) America, Jamaica. Foss. Paris, Dax. 



(2) Spondyli are frequently eaten ; their shells are often tinted with the liveliest 

 colors, and adhere to all sorts of substances. Several species abound in tem- 

 perate climates, but they are principally found in the seas of warm countries. 

 Foss. at Turin, Grignon, Havre. 



(3) Known only in the fossil state, and is found in England, in France, at 

 Touraine, Mcudon, Dax, and in Italy. 



(4) Known only in the fossil state, and found in England at Colebrook Dale, at 

 Toddenham in Gloucestershire, at Fenny Compton, and at Cheltenham in upper beds 

 of Lias. 



A 



