44 CONCHOLOGY. 



N. Tellinaria. Seven genera. 



The first five of these genera have one or two lateral teeth, 

 the remaining two have none. 



4. Tellina. The Tellen. Fifty-four species. 



This genus differs but little from the Donax ; its species 

 are numerous, especially in the seas of hot countries ; they 

 are found sunk deep in the sand. 



There are but few genera that can vie with the Tellina in 

 beauty, variety, or number ; some are smooth and polished, 

 some are remarkable for their beautiful radiations, and others 

 are covered with minute striae and undulations ; occasionally 

 the whole surface is covered with imbrications or scales. 



They are produced abundantly in almost every sea and 

 in many rivers, but the finest species are found in the pearl- 

 fisheries of Ceylon. 



The usual form of the Tellina is broad at one end and 

 gradually tapering towards the other. It derives its name 

 from the Greek word reXeio), to bring to a termination. 



Shell of variable form, generally striated longitudinally 

 and very compressed ; equivalve, more or less inequilateral ; 

 anterior side longer and more rounded than the posterior ; 

 offers a flexuous plait or twist at the inferior margin ; sum- 

 mits little marked ; hinge similar ; one or two cardinal 

 teeth ; two distant lateral teeth, with a pit at their base in 

 each valve ; ligament external. 



