CONCHIEERA. 



229 



Semele. 



Many species 



Semele. Schum. ( Amphidesma Lam.) — Shell equi- 

 valve, round or rather oblong, inequi- 

 lateral, and closed, with a slight wave 

 or fold like that of Tellina ; two small 

 cardinal teeth and a long narrow pit 

 between ; large lateral teeth ; ligament 

 both external and internal, and with- 

 out a special hinge plate; mantle 

 sinus round and deep. Animal unknown, 

 also fossil. 



These shells are found in the sand on the sea-coasts of 

 tropical countries ; and also those of England and Holland. 

 They have, many of them, transverse stripes, and usually, 

 moreover, fine stripes radiating from the bosses. 



Cumingia. Sow. — Shell equivalve, inequilateral, trans- 

 verse, rounded anterioriiy, subros- 

 trated posteriorily ; hinge with a 

 central spoon-shaped cavity in each 

 valve, containing the cartilage ; a 

 very small anterior cardinal tooth in 

 each valve ; two lateral teeth in one 

 valve, none in the other ; muscular 

 impressions two in each valve, distant, 

 pallial with a very large posterior 



sinus.* Animal unknown. — About 6 species ; also fossil. 

 Found in sand in the American seas and in the tropics. 



Scrobicularia. Schum. (Lavignon Cuvier ; Arenaria 

 Muhlf. ; Listera Turton.) — Shell with no lateral teeth, 

 but with one or two small cardinal teeth, and the internal 

 cartilage placed in an oblique spathula fulcrum in each 

 valve ; pallial sinus ample ; ligament small, narrow, par- 



* Sow., Conch. Manual. 

 q 3 



