188 



being distinct and forward ; the lateral teeth remote ; the 

 ligament external. 



Venus paradoxa, Born. Galathea radiata^ Ann. du Mus. 

 Tom. 5. PI. xxviii. 



ConchcB Marini. — Rarely with epedermis, or lateral 

 teeth. 



1. Cyprina. — An equivalved, inequilateral, and obliquely 

 cordated bivalve ; three unequal cardinal teeth : one lateral 

 tooth on the anterior side, sometimes obsolete. 



2. Cytherea. — An equivalved, inequilateral, suborbicular, 

 trigonal or transverse shell ; four cardinal teeth on the right 

 valve ; three diverging, approximated at their base, and one, 

 entirely separate, under the lunule ; three diverging cor- 

 responding teeth in the other valve ; with a separate pit for 

 the separate tooth of the other valve. No lateral teeth. 

 Recent and fossil. — PI. viii. fig. 13. 



3. Venus. — An equivalved, inequilateral, transverse, or 

 suborbicular shell ; three cardinal approximated teeth on 

 each valve, the lateral one^ diverging from the summit; the 

 ligament external. Recent and fossil.-^Pl. viii. fig. 7. 



Cardiacece. — Teeth irregular either In form or situation. 



1. Venericardia. — An equivalved, inequilateral, subor- 

 bicular bivalve, most commonly with longitudinal ribs ; the 

 hinge, two cardinal teeth, nearly in the same direction. 

 Recent and fossil. — PL. viii. fig. 2. 



2. Cardita. — A free, inequilateral, equivalved bivalve; 

 the hinge with two unequal teeth, one short and straight 

 under the beaks, the other oblique and marginal, extended 

 beneath the corselet. Recent and fossil. — PI. vli. fig. 27. 



3. Cardium. — A subcordiform equlvalve, protuberant at 

 the base, the valves plicated or dentated on their inner 

 margin. The hinge with four teeth in each valve ; two 

 oblique approximating cardinal teeth, those of each valve 



