216 MALACOZOA. TROPIOPODA. LAMELLIBRANCHlA'TA. 



rather thick, with numerous close concentric small ridges, 

 whitish with pink rays. Crdssus, thick. 



3. Tellina tenuis. — Shell ovate, compressed, very thin, 

 glossy, concentrically striate, white, yellow, or pink. 

 Tenuis, thin. 



4. Tellina Fdbula. — Shell ovate, compressed, very 

 thin, glossy, white, with one valve concentrically, the 

 other obliquely striate. Fdbula, a small bean. 



Family IX. — Solenina. 



Animal much elongated, with the mantle closed, but 

 having an opening in front for the foot, and forming 

 behind a tube, internally double ; the foot conical. 

 Shell long, equivalve, extremely inequilateral, thin, gap- 

 ing at both ends, and covered with epidermis ; the hinge 

 with not more than two small, prominent teeth in each 

 valve ; the ligament linear and dorsal. Named from the 

 genus Solen. 



Genus 1 . Solen. — Shell extremely elongated, linear or 

 oblong, equivalve, extremely inequilateral ; umbones 

 very small, near one end; cardinal teeth very small. 

 Sdlen, a razor-shell. Linnaeus. 



1 . Sdlen Siliqua. — Shell extremely elongated, slender, 

 straight, truncate at both ends. Siliqua, a pod. 



2. Solen Ensis. — Shell extremely elongated, slender, 

 rearcuate, truncato-rotundate at both ends. Ensis, a 

 sword. 



3. Solen pellucidus. — Shell much elongated, linear- 

 oblong, slightly recurved, rounded at both ends. Pel- 

 lucidus, permeable to light. 



Genus 2. Psammobia. — Shell oblong or elliptical, in- 

 equilateral; umbones very small; cardinal teeth very 

 small. tydfjifMos, sand ; /3ioa>, to live. Lamarck. 



1. Psam?ndbia Feroensis. — Shell oblong, much com- 

 pressed, anteriorly rounded, posteriorly obliquely trun- 

 cate, finely striated concentrically, with a prominent line 

 from the umbo to the posterior angle. Named from its 

 occurring in Feroe. 



