DIPI.ODON 1307 



Unio angasi Sowerby, Conch. Icon., XVI, 1867, pi. i^v, fig. 282. 

 Margaritana angasi Fa'.tei., Conch. Sam., Ill, 1890,- p. 172. 

 Anodonta angasi P.^tel, Conch. Sam., HI, 1890, p. 176. 



A most striking species, which until lately has appeared to 

 be quite distinct from any other. The sculpture of the pos- 

 terior part of the shell extends forward to an oblique line in 

 front of and nearly parallel with the posterior ridge covering 

 over half of the shell. In some specimens there is more or 

 less feeble, nodulous sculpture in front of this line. The dark 

 thick epidermis is inclined to peel off : the pallial line is decid- 

 edly crenate. 



DiPLODON wEP>STERi Simpson. 



Shell long rhomboid, compressed, inequilateral, subsolid 

 when young, rather solid when old ; beaks low, subcompressed, 

 pointed, their sculpture consisting of a few, curved, subradial, 

 broken bars ; anterior end rounded, developed almost into an 

 angle above ; base line nearly or quite straight, parallel with 

 the dorsal line ; posterior end rounded below, obliquely trun- 

 cate above, the point of junction of this truncation with the 

 dorsal line almost angulate ; posterior ridge low and rounded ; 

 surface with strong, irregular, concentric growth lines and 

 covered throughout with pustules ; these are strongest and 

 somewhat lachrymose on the disk in front of the posterior 

 ridge : in young shells there is a short row of strong, irregular 

 knobs on the posterior ridge ; epidermis yellowish-ash to dark 

 brown or blackish-clouded green in young shells, nearly uni- 

 form black in old ones ; left valve with two small, subcompress- 

 ed, granular pseudocardinals and two remote, straight later- 

 als, the upper the stronger ; right valve with two pseudocar- 

 dinals, the upper small, with one lateral ; dorsal scars few, 

 placed well below the hinge line ; adductor scars shallow ; nacre 

 bluish-white, blotched in the cavities, greatly thickened on the 

 anterior base in old shells. 



Length 6"/, height 33, diam. 14 mm. 



Waiuku, New Zealand. 

 Diplodofi zcehsteri Simpson, Naut., XVI, 1902, p. 30. — Daee, 



Proc. U. S. Nat. Mus.. XXXV, 1908, p. t8i, pl.\xx. figs. 



I, 2. 



