MALACOZOA. TIlOPlOrODA. LAMELLIBUAN'CHIATA. 219 



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

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

 cate behind ; umbones small ; hinge ^vitli an abrupt sinus 

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

 eaten by sea-ducks. Lamarck. 



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

 the anterior end rounded, the posterior subtruncato- 

 rotundate and roughish with minute prominences. 

 PrcetSnuis, very thin. 



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

 pressed, the anterior end rounded, the posterior narrowed, 

 subtruncate, and roughish with minute prominences. 

 Ti'uncdtus, cut short. 



Genus 6. Thracia. — Shell ovato-oblong, inequivalve, 

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

 truncate beliind; umbones rather prominent ; hinge with 

 a horizontal, oblique, concave tooth. Deshayes. 



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

 •with the posterior end narrowed, compressed, roundly 

 truncate. Decl'ivis, sloping. 



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

 compressed, very thin, with the posterior end truncate, 

 the surface very minutely punctulate, roughish behind. 

 Pubcscens, 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 eUiptical, 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 

 smaU ; hinge strong, with a horizontal spoon-shaped 

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

 Linnaeus. 



