CO xc HO war. 137 



FamiJij Glauconomyidse. 



Foot modorntoly large, thick, comjji'esscd, kcck'd. Siphons very long. Shell 

 oblong, thin, vciitricose, covered with ;i green epidermis. 



Gl.vucono.m ya, Bronn. 



Hinge narrow, with three teeth in each valve, the middle teeth in the loft and 

 the hinder one in the right valve, bifid. Ligament external. I'allial sinus deep. 

 Inhabits fresh and brackish waters. 



* ,, cnrxKXSis, Gray. 

 NovACfLixA, Benson. 



Beaks subposterior. Shell covered with a thin wrinklcil epiderniis. 



* ,, GANGETICA, 13. 



This is a fresh-water spccios found in rivers above the tideway, but growing, I 

 think, largest in mud banks within tidal influence. 



Fmnihj Corbulidae. 



Siphons short, the anal furnished with a tubular retractile valve. Dody 

 imsymmetrical. Foot long with a byssal groove. 



CoEDtTLA, Britgum-e. 



Shell ovate, gibbous, very inequivalve, beaks prominent, valves concentrically 

 striated. Hinge a recurved tooth in tlu; right valve, received into a cartilaginous 

 process in the left. Ligament small, internal. 



,, KoiiTisri.CATA, E. A. Smith. Andamans. 



SriiERiA, TiirtoH. 



Shell oblong, inequivalve, produced and gaping postenorly. Surface smooth or 

 nigose, covered with an epidermis. Hinge a dilated laminar tooth in front of the 

 oblicpie cartilage-pit in the right valvo, with a corresponding pit in the left cartilage 

 internal. 



,, PERVERSA, "VV. Blanford. Irrawaddy Delta. 



Family Anatinidse. 



Shell thin, nacreous, inequivalve. Hinge teeth rudimentary. Ligament external. 

 Cartilage internal, in a pit in each valve, usually furnished with a free ossicle. 



Anatina, Lamarck. 



Siphons long, covered with a rugose epidermis. Cartilage-pit in each valvo 

 spoon-shaped, projecting internally, furnished in fi'ont with a transverse ossicle. 



* ,, BoscHASiANA, Rcevc. 



Pandora, Solander. 



Siphons very long. Shell thin, inequivalve, closed, pearly within. Right valvo 

 flat. Ligament internal. Hinge with a primary tooth in each valvo with correspond- 

 ing cartilage-pits, but no fr-ee ossicle. 



* ,, Ceylakica, Sow. 



Family Gastrochaenidae. 



Siphons very long, united almost to their ends. Foot small, not bys.siferous. 

 Shell e(|uivalve, valves gaping. Hinge rudimentary. Cartilage external, small, weak. 



The Gaslroclucnidce, together with the Pholadcs, constitute the Tuhicola of 

 Lamarck, a very natural group characterized by their living chiefly inclosed in tubes 

 or burrows which they never leave. The valves of the shell arc sometimes firmly 



