180 



The three preceding genera bear somewhat of the form 

 of tellens, 



4. Tellina. — A transver&e or orbicular shell, for the most 

 part flattish ; angular on the anterior side, on which is a 

 flexuous and irregular fold ; one or two hinge teeth on the 

 same valve ; two lateral teeth, generally remote. Recent 

 and fossil. — PI. viii. fig. 16. 



5. TelUnides, — A transverse, inequilateral shell, rather 

 flat, and slightly gaping at the sides ; the beaks small ; no 

 fold on the margin ; the hinge with two diverging teeth on 

 each valve ; two lateral, nearly obsolete, teeth, the posterior 

 one of which, in one valve, is placed near to the hinge. 



Only one species is known. Recent. 



6. Corhis. — A transverse, equivalved bivalve, without 

 any irregular fold at the anterior border ; the beaks curved 

 inwards, opposite to each other ; two hinge teeth ; two 

 lateral teeth, the hinder of which comes near to the hinge ; 

 the impressions simple. Recent and fossil. 



Separated from liicina by the impressions not being com- 

 plicated ; and, from tellinay by having no fold. 



7. Lucina. — A suborbicular, inequilateral bivalve, with 

 small, pointed, oblique beaks ; two diverging hinge teeth, 

 one of which is bifid, these being variable or disappearing 

 with age ; two lateral teeth, one of which approaches the 

 hinge ; two lateral impressions, one of which is considerably 

 extended posteriorly ; the ligament external. Recent and 

 fossil. — PI. viii. fig. 15. 



8. Donax. — A transverse, equivalved, inequilateral bi- 

 valve, the anterior side very short and obtuse ; two hinge 

 teeth on each valve, or on one only ; one or two lateral 

 teeth, more or less remote ; the ligament external, short, 

 and at the lunule. Recent and fossil. — PI. viii. fig. 11. 



9. Capsa. — A transverse, equivalved, close shell, the 

 hinge having two teeth on the right valve, and one bifid 

 penetrating tooth in the other valve ; no lateral teeth ; the 

 ligament external. 



