304 CATALOGUE OP THE SPECIES OF 



Grateloupea (Des Moulin). 



Shell ovate, edge entire. Hinder hinge tooth deeply transversely 

 divided into lobes ; anterior lateral tooth short, large. Syphonal 

 inflection moderate. 



Gratel. irregularis (Donax irregularis, Basterot). 



Gratel. hydana (Cytherea hydana, Conrad; Grat. Moulinsii, 

 Lea.) — Fossil, lower tertiary, America, Alabama. 



Gr. cuneata, n. s. — Shell thick, wedge-shaped, round, and rather 

 produced in front. The umbones rather behind the middle. — Fossil, 

 my collection. 



Trigona (Megerle). 



Shell triangular, edge even. Hinder hinge tooth torn. Anterior 

 lateral tooth elongated, compressed far from the others. 



Trigona donacoides ( Venus donacoides, Gray, Wood, Supp., t. 2, 

 f.17- 



Trigona stultorum (Venus stultorum, Gray, Wood, Supp., t. 2, 

 £2. 



* With three narrow laminar, sloping, hinder teeth in the right 

 valve ; hinder lateral teeth long. 



Trigona Byronensis. — Shell trigonal, cordate, rather ventricose, 

 white, with interrupted brown rays, and zig-zag brown lines on the 

 slope ; lunule white ; inside white ; umbones purple. 



Var. — Shell white, without rays or lines. 



Inhabits Pacific Ocean. — Capt. Lord Byron. 



'** And with two large, oblique hinder teeth in the right valve, 

 inner one largest ; lateral teeth short. 



Trigona corbicula ("Venus corbicula, Lam.) 



Trigona ventricosa. — Shell ovate, trigonal, ventricose, pale brown. 

 Hinder slope flattened, very broad. 



Trigona planulata, Sow., Gen., f. 2. — Shell trigonal, thin, rather 

 compressed, whitish, with unequal brown rays. Umbones purple 

 with two white rays ; inside purple, white-edged. 



