CONCHIFEKA. 313 



low, triangular ; hinge-teeth small, 1 or 2 in each valve, laterals obsolete 

 pallial sinus wide and deep. 



Animal with the mantle open, margins denticulated ; siphons very long, 

 slender, separate, orifices plain ; foot large, tongue-shaped, compressed ; palpi 

 very large, triangular, gills minutely striated, the outer pair directed dorsally 

 Lives buried, vertically, in the mud of tidal estuaries, 5 or 6 inches deep 

 {Montagu.) The siphons can be extended to 5 or 6 times the length of the 

 shell. {Deshayes). The animal has a peppery taste, but is sometimes eaten 

 on the coasts of the Mediterranean. Distr. Norway, Brit. Medit. Senegal. 

 Fossil, Pliocene, Brit. 



Mesodesma, Deshayes. 



Etym. Meso- middle, desma ligament. Syn. Eryx, Sw. (not Daud.) 

 Paphia (part) Lam. 1799 (see p. 299, note). Erycina (part) Lam. 1818 (not 

 Lam. 1805, nor Eabr. 1808). " Donacille," Lam. 1812 (not characterized). 



Examples, M. glabratum, PI. XXI. fig. 15. M. donacium. fig. 16. 



Shell trigonal, thick, compressed, closed; ligament internal, in a deep 

 central pit; a minute anterior hinge-tooth, and 1—1 lateral teeth in each 

 valve ; muscular scars deep , pallial sinus small. 



Animal with mantle-margins plain ; siphons short, thick, and separate^ 

 orifices cirrated, branchial cirri dendritic ; foot compressed, broadly lanceo- 

 late : giUs large, unequal ; palpi small. 



Sub genus. Anapa, Gray. A. Smithii, PI. XXI. fig. 17. Umbones 

 anterior, siphonal inflection obsolete. 



Bistr. 20 sp. "W. Indies, Medit. Crimea, India, New Zealand, Chili ; 

 sands at low-water. 



Fossil, 7 sp. Neocomian — . U. S. Europe {Botiacilla, D'Orb.) 



Ervilia, Turton. Lentil-shell. 



Htym. Ervilia, diminutive of ervum, the bitter- vetch. 



Type, E. nitens, P. XXI. fig. 18. 



Shell minute, oval, close ; cartilage in a central pit ; right valve with a 

 single prominent tooth in front and au obscure tooth behind ; left valve with 

 2 obscure teeth ; no lateral teeth ; pallial sinus deep. 



Distr. W. Indies, Brit. Canaries, Medit. Red Sea. — 50 fms. 



DoNAx, L. Wedge- shell. 



Ex. D. denticulatus, PI. XXI. fig. 19. Etym. Donax, a sea-fish, Pliny. 



Syn. Chione Scop. Cuueus, Da Costa. Capisterium, Meusch.* Latona 

 and Hecuba, Schum. Egeria, Lea (not Roissy). 



Shell trigonal, wedge-like, closed; front produced, rounded; posterior 

 side short, straight ; margins usually crenulated ; hinge-teeth 2.3 ; laterals 



* Meuschen was a Dutch auctioneer; the names occur in his " sale catalogues." 

 Idiotce imposuere nomina absurda. Linnaeus. 



