CONCHIFERA. 293 



mouth minute, lips thin ; gills single on each side, very large and thick ; 

 foot cylindrical, pointed, slightly heeled at the base. 



The foot of Lucina is often twice as long as the animal, but is usually 

 folded back on itself and concealed between the gills ; it is hollow throughout. 

 L. lactea (Loripes, Poli.) has a long, contractile anal tube. L. tigrina 

 (Codakia, Scop.) has the ligament concealed between the valves, its lateral 

 teeth are obsolete. 



Distr. 70 sp. W. Indies, Norway, Black Sea, N, Zealand ; 120 fms. 



Fossil, 200 sp. U. Silurian . U. States T. del. Fuego ; Europe 

 S. India. 



Sub-genus, Cryptodon, Turton. L. flexuosa, PI. XIX. fig. 7. Syn. 

 Ptychina, Phil, Thyatira, Leach. Clausina (ferruginosa) Jeflr. Shell 

 thin, edentulous ; ligament quite internal, oblique, Animal with a long anal 

 tube. Distr. Norway N. Zealand. Fossil, Eocene . U. S. Europe. 



CORBIS, Cuvier. 



Etym. Corbis, a basket. Type, C. elegans. PI. XIX. fig. 8. 



Syn. Fimbria, Muhl. not Bohadsch. " Idotsea," Schum. 



Shell oval, ventricose, sub-equilateral, concentrically sculptured ; margins 

 denticulated within ; hinge-teeth 2, laterals 2, in each valve ; pallial line 

 simple ; umbonal area with an oblique furrow, muscular impressions round 

 and polished ; pedal scars close to adductors. 



Animal with the mantle open below, doubly fringed ; foot long pointed ; 

 siphonal opening single, with a long retractile tubular valve ; lips narrow ; 

 palpi rudimentary; gills single on each side, thick, quadrangular, plaited, 

 united behind. 



Distr. 2 sp. India, China, N. Australia, Pacific. 



Fossil, 80 sp. (including sub-genera). Lias . U. States, Europe. 



In C. dubia (Semi-corbis) Desh. Eocene, Paris, the lateral teeth are 

 obsolete. 



Sub-genera. Sphcera (corrugata) Sby. Shell globular, concentrically 

 furrowed and obscurely radiated ; ligament prominent ; margins crenulated ; 

 hinge-teeth 2.2, obscure ; laterals obsolete. Fossil, Trias Chalk. Europe. 



? Unicardium, D'Orb. (Mactromya, Ag. part) = Corbula cardi- 

 oides, Sby. Shell thin, oval, ventricose, concentrically striated; ligamental 

 plates elongated ; pallial line simple ; hinge with an obscure tooth, or eden- 

 tulous Fossil, 40 sp. ? Lias Portlandian. Europe. 



? TANCREDIA, Lycett, 1850. 



Dedicated to Sir Thos. Tancred, Bt. founder of the Cotteswolde Natu- 

 ralists Club. 



Ex. T. extensa, L. PI. XXI. fig. 22. Syn. Hettangia, Turquem. 

 Shell trigonal, smooth; anterior side usually longest; cardinal teeth 



