APPENDIX. 251 



open its closed valves; the peculiar dentition was, consequently 

 not observed. 



The valves are furnished with a short hinge-plate that extends 

 only immediately beneath the umbones. In the right valve this 

 plate is armed, just below the beak in front, with a strong and 

 prominent bluntly cloven tooth, which rising from the lower edge, 

 curves with some slight obliquity upwards ; a short and very 

 small triangular cartilage-pit occupies the upper portion of the 

 area behind it ; the rest of the surface, which is more or less tri- 

 gonal, is level or slightly hollowed. In the left valve, the hinder 

 half of the plate is slightly hollowed out, excepting at the lower 

 edge, as a subtrigonal shallow depression, that is barely divided in 

 front below by an obscure thin ridge, from the tiny but deep tri- 

 angular excavation (which receives the opposite tooth) ; the re- 

 maining level or slightly raised anterior surface, which projects a 

 little, with a somewhat bifid extremity, above the latter, into the 

 larger triangle, suggests the idea of a complicated dentition. 



Vol. i. p. 284. Diodonta eragilis. 



The Galway coast furnishes this local shell in comparative 

 abundance (Dr. Melville). 



Vol. i. p. 290. Tellina balaustina. 



Mr. Barlee has dredged this beautiful species at the Arran 

 Isles, on the west coast of Ireland, and also on the north, east and 

 west of the Zetland Isles. 



Vol. i. p. 295. Tellina pygmjea. 



Mr. Hanley has recently dredged it near St. Peter's Port, 

 Guernsey. 



Vol. i. p. 307. Tellina proxima. 



Plate CXXXIII., f. 3. 



Since our notice of this species, a single valve (that delineated 

 in our engraving), together with the fragment of two united by 



