APPENDIX. 361 



The umbo scarcely produced, in the middle of the shell, 

 inside white. 



Length, 1 inch; height, 1\ lines; thickness, 4^ lines. 



Inhab. — Van Diemen's Land, Hobart Town. Mr. 

 Cuming^s cabinet. 



It should be observed that the superficial ridges of this 

 species, as in many others of the genera, are not concentric 

 with the margin of the valve, but are commenced in the 

 middle of the lower edge and the outer one, (as does also 

 the second), terminates before it reaches the end of the 

 shell. 



Moldia Mullen. 

 Marine Shells, Plate 2,/. 4. 



Shell oblong, subquadrangular, smooth, dark olive brown, 

 with a paler marginal zone, rather more than half as long 

 again as high, rounder at each end, the hinder end highest. 



Length, 1 inch 3 lines; height, 1 inch ; thickness, 7 lines. 



Inhab. — Port Essington. Cabinet of Mr. Cuming. 



Trigonia uniophora. 

 Marine Shells, Plate 2,/. 5. 



Shell reddish brown, with twenty-two or twenty -three 

 high, rather compressed, rather close diverging ribs, the 

 upper part of the central, and the whole of the posterior 

 lips covered with close, regular transverse plates ; the ante- 

 rior and the lower part of the central ribs with large 

 roundish or oblong solid tubercles. 



The hinder slope with five or six nodulose ribs. 



Inhab. — Cape York, in 6 fathoms. Cabinet of Mr. 

 Cuming. 



