242 COl!iGRYUA—DITHYRA. 54. 



54. UmO—BRUGUIERE. 



Testa transversa, cequivalvis, itKequilateralis, lateribus subhiantibus ; 



umbonibus eroso-decorticatis. Cardo dente conico obtuso laciniato, 



valv(B alterius bilobo ; et sinu marginali antico remoto : lateralibus 



nullis. Ligamentum externum. 

 Shell transverse, equivalve, inequilateral, a little open at the sides ; 



with the beaks decorticated and eroded. Hinge with an obtuse 



conic jagged tooth, which in one valve is divided into two lobes ; 



and a remote cardinal depression on the anterior side : lateral 



teeth none. Ligament external. 



A genus distinguished from the Anodon, by the conic obtuse 

 rugged teeth, and from the Mysca and Cyclas by the want of lateral 

 teeth ; and by the cavity on the cardinal margin at the anterior 

 . termination of the ligament. 



Inhabitants of clear rapid rivers, where they lie imbedded in the 

 gravel, with the anterior end just above the surface, and are often 

 rooted up and cast on shore by floods and torrents. The valves are 

 used as spoons by the Irish peasantry. 



inaigaritUe- Unio testd oblongd subarcuutd, latere antico angulato. 



'"**■ Shell oblong and slightly curved, angular at the anterior side. 



Tab. nost. 16, fig. 1. 

 Mya niargaritifera. Linn. Syst. Nat. p. 1112. 

 Gmelin, Syst. p. 3219. 

 Turton, Linn. Syst. iv. p. 1 76. 

 Pennant, iv. p. 163, tab. 46. fig. 2. 

 Chemnitz, vi. p. 15, tab. 1, fig. 5. 



