CONCHYLW—niTHYKA. 49. 221 



with pale rays: beaks separated by a linear transverse cavity: 

 inside perlaceous, a;lossy except round tlie niarjjin, which is 

 extremely thin : hinge with a single small tooth under tbe beak, 

 wiiich forms a slight indentation in the opposite valve. 



49. Fl^^X—LINN]^. 



Testa longitudinalis cuneiformis a^quivalvis, basi aculd rectius- 



culd, apice dilatato hiante. Cardo edentulus. Ligamentum 



externum, proilongum. 

 .Shell longitudinal, wedge-shaped, equivalve, pointed and nearly 



straight at the base, dilated and open at the top. Hinge 



without teeth. Ligament external, and very long. 



These shells have a wedge-form or somewhat triangular shape, 

 and are fixed in gravelly and sandy parts of the ocean by the 

 pointed end, near the termination of which issues a strong hair- 

 like byssus of attachment. 



Pinna testa ovato-trigond, strii^ transDersis arvuatis, apice iugens 



fastigiato, latere postico truncato recto. 

 Shell oval-triangular, with transverse arched striae, flat at top 



truncate and straight at the hinder side. 



