498 MANUAL OF THE M0LLF8CA. 



? Cardiomorpha, Koninck. 



Type, C. oblonga (Isocardia), Sowerby (not Koninck). Car- 

 bonate of lime. 



Shell Isocardia-sbaped, smootb or concentrically furrowed, 

 umbones prominent, hinge edentulous; hinge-margin with a 

 narrow ligamental furrow, and an obscure internal cartilage 

 groove. 



Fossil, 38 species. Lower Siluiian — Garb. North America, 

 Europe. 



Edmondia, Koninck. 



Example, E. sulcata, Ph. (T. Pal. Soc. 1850, PI. XX., Fig. 5.) 

 Carb. Britain. 



Synonyms, AUorisma, King (part). Sanguinolites, M'Coy 

 (part). 



Shell oblong, equiyalve, thin, concentrically striated, close ; 

 umbones anterior ; ligamental grooves narrow, erxternal ; 

 hinge-line thin, edentulous, furnished with large oblique 

 cartilage plates, placed beneath the umbones, and leaving space 

 for an ossicle ? or the plate may be equivalent to the sub-um- 

 bonal blade in Pholas ; pallial line simple ? 



Fossil, 4 species. Carb. — Permian. Europe. 



Sub-genus. Scaldia, Eyckholt, 1856. Carb. Tournay. Shell 

 like Edmondia, with a single cardinal tooth in each valve. 



Lyonsia, Turton, 1822 (not E. Brown). 



Synonyms, Magdala, Leach, 1827. Myatella, Brown. Pan- 

 dorina, Scacchi. 



Type, L. Norvegica, PI. XXIII. , Fig. 10. 



Shell nearly equivalve, left valve largest, thin, sub-nacreous, 

 close, truncated posteriorly ; cartilage plates oblique, covered 

 by an oblong ossicle ; pallial sinus obscure, angular. Struc- 

 ture intermediate between Pandora and Anatina ; outer layer 

 composed of definite polygonal cells. 



Animal with the mantle closed ; foot tongue-shaped, grooved, 

 byssiferous; siphons very short, united nearly throughout, 

 fringed ; lips large, paljpi narrow, triangular. 



Distribution, 12 species. Greenland, North Sea, Norway, 

 West Indies, Madeira, India, Borneo, Philippines, Peru. 



L. Norvegica ranges from Norway to the sea of Ochotsk ; ixi 

 15—80 fathoms 



