MALACOZOA. TROPIOPODA. LAMELLIBRANCHIATA. 219 



Genus 5. Anatina. — Shell oval, inequivalve, inequi- 

 lateral, very thin, brittle, gaping and more or less trun- 

 cate behind ; umbones small ; hinge with an abrupt sinus 

 and a projecting spoon-shaped lamina. Anas, a duck ; 

 eaten by sea-ducks. Lamarck. 



1 . Anathia prcetenuis. — Shell ovate, rather compressed, 

 the anterior end rounded, the posterior subtruncato- 

 rotnndate and roughish with minute prominences. 

 Prcetenuis, very thin. 



2. Anathia truncdta. — Shell subovate, rather com- 

 pressed, the anterior end rounded, the posterior narrowed, 

 subtruncate, and roughish with minute prominences. 

 Truncdtus, cut short. 



Genus 6. Thracia. — Shell ovato-oblong, inequi valve, 

 inequilateral, very thin, brittle, gaping and more or less 

 truncate behind; umbones rather prominent ; hinge with 

 a horizontal, oblique, concave tooth. Deshayes. 



1. Thracia declivis. — Shell oval, convex, very thin, 

 with the posterior end narrowed, compressed, roundly 

 truncate. Declivis, sloping. 



2. Thracia pubescens. — Shell ovato-oblong, somewhat 

 compressed, very thin, with the posterior end truncate, 

 the surface very minutely punctulate, roughish behind. 

 Pubescens, downy. 



Family II. — Myina. 



Animal elliptical, ovate or oblong, compressed, with 

 the mantle closed beneath, open in front for the foot, 

 and forming behind two long united or separated tubes ; 

 foot small, compressed, tapering ; shell elliptical, oval, 

 or oblong, generally inequivalve, gaping at both ends ; 

 the hinge with a concave tooth in one valve, and a cor- 

 responding depression in the other for the ligament- 



Genus 1. Mta. — Shell ovate or oblong, inequivalve, 

 inequilateral, convex, gaping at both ends ; umbones 

 small ; hinge strong, with a horizontal spoon-shaped 

 process ; ligament internal. Mvag, a kind of shell-fish. 

 Linnseus. 



