CONCHYLIA-DITHFi?^. xiii\ 



32. Capsa. — Testa cuneaia, ligamento ad latus brevissimum. 



Shell wedge-shaped, with the ligament at the 

 shortest side. 



17. Agina. — Testa transversa, dente conico in utraque valvd. 

 Shell transverse, with a single conic tooth in 

 each valve. 



30. Cryptodon. — Testa trigono-glohosa, dente unico ohsoleto in 

 utraque valvd cum fovea transversd. 

 Shell triaugular-globular, with a single obscure 

 tooth in each valve and a transverse cavity. 



26. PsAMMOBlA. — Testa ohlonga vel ovata, lateribus subhian- 

 tihus, dentibus subbinis. 



Shell oblong or oval, a little open at the sides, 

 Yvith two teeth in one or both the valves. 



5. HiATELLA. — Testa iiicequivalvis, medio vel latere antico 

 liiante, dente tmico inter duos penetrante. 

 Shell inequivalve, open in the middle or at the 

 anterior end, with a single tooth in one valve 

 closing between two in the other. 



.33. Crassina. — Testa clausa, dentibus duobus itt utraque valvd. 

 Shell closed, with two teeth in each valve. 



28. LuciNA.— y^i^a clausa, dentibus duobus vel tribus cumfoveoM 

 laterali transversd. 



Shell closed, with two or three teeth and a 

 lateral transverse hollow. 



