CONCHOLOGY.. 
shaped tooth: and: an adjacent: triangular’ one : 
lateral teeth none. 
Includes Mactra hians; and lutraria, 
49, Montacuta, Shell oval or oblong, equivalve; 
inequilateral; mostly closed. Hinge with two 
teeth in. each: valve, and:a cavity between them: 
lateral teeth none. 
Includes Mya _ substriata;. bidentata, and 
ferruginea, 
50.. Pandora, Shell: transverse,, inequivaive, 
inequilateral, open at the anterior end. Hinge of 
the flat valve with a single tooth and longitudinal 
cavity, of the convex: valve with two longitudinal: 
cavities ; lateral teeth none. 
Includes Tellina inequivalvis; and obtusa. 
51. Corbula. Shell somewhat triangular, ines 
quivalve, imequilateral, closed. Hinge with a 
single conic tooth and adjacent cavity in the left 
valve, and a spoon-shaped tooth: and cavity’ in 
the right : lateral teeth none, 
Includes the Mya inequivalvis: 
52. Mactra. Shell somewhat triangular, equivalve, 
a little open at the sides, Hinge witha spoon 
shaped tooth, and.an adjacent triangular one: 
lateral teeth, laminar, double in one of the valves, 
Includes Mactra solida crassa, subtruncata; 
stultorum. 
53. Lepton. Shell flat, nearly orbicular, inequi- 
lateral, a little open at the sides. Hinge of one 
valve with a single tooth, and transverse linear 
lateral one on each side; of the°other:valve-with 
