192 DESCRIPTION OF 



Shell oval, rather compressed; substance of the shell very thin and transpa- 

 rent; beaks somev^'hat prominent; ligament long and thin; epidermis polished, 

 dark, the w^hole disk being nearly covered with deep green rays; cardinal teeth 

 lamellar, erect, pointed; lateral teeth long, lamellar and somew^hat curA^ed; ante- 

 rior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices placed 

 across the cavity of the beaks; cavity of the shell shallow; cavity of the beaks 

 shallow and somewhat angular; nacre blue and very iridescent behind. 



Remarks. — This species is nearly allied to U. iris (nobis.) Like it, it has 

 numerous green rays passing over the whole disk, more dense on the posterior 

 portion. It differs in being less transverse and being apparently without 

 undulations at the beaks, those of the ij-is being remarkable. The cardinal 

 tooth in the left valve is but slightly cleft, and the anterior portion is more 

 elevated and pointed. 



TJnio cucumoides. Plate 7, Fig. 2. 



Testa plicatd, emarginatd, latissima, suhcylindraced; valvulis subcrassis ; natibus vix prominentihus ; 

 epidermide nigra ; dentibus cardinalibus parvis, tuberculatis ; later alibus longissimis rectisque; mar. 

 garita alba. 



Shell folded, emarginate, very broad, somewhat cylindrical; valves rather thick; beaks scarcely promi- 

 rent; epidermis black; cardinal teeth small, tuberculate; lateral teeth very long and straight; nacre white. 



Hab. Hunter's River, New South Wales. Dr. Jay. 



Cabinet of Dr. Jay. 

 Diam. 1.4, Length 2.2, Breadth 5.5 inch. 



Shell folded over the posterior half, emarginate at base, very broad, some- 

 what cylindrical, subbiangular behind ; folds small and numerous; substance 

 of the shell rather thick, thinner behind; beaks scarcely prominent and placed 

 near to the anterior margin; hgament very long and thick; epidermis black; 

 cardinal teeth small, tuberculate; lateral teeth very long and straight; anterior 

 cicatrices confluent; posterior cicatrices confluent; dorsal cicatrices placed in a 

 row across the centre of the cavity of the beaks; cavity of the shell deep and 

 rounded; cavity of the beaks very small ; nacre white. 



