DirLODON 1295 



widely rounded below and ending in a blunt point at the base 

 of the shell ; there is in most cases a sort of low, short, radial 

 anterior ridge at the umbonal region and between this and the 

 posterior ridge there is a radial depression ; surface with ir- 

 regular, concentric sculpture : occasionally showing faint cor- 

 rugations on the disk ; epidermis thick, blackish sometimes 

 tinted brownish or greenish ; pseudocardinals small, stumpy in 

 old shells, but compressed in yoimg ones; laterals granular; 

 nacre bluish, thicker in front. 



New Zealand. 

 Uiiio :;elchori Dunkhr. Reise der Nov.. 1867, P- ^S; P^- H- fig- 



28. 

 Margaron (Unio) zclcbori Lka. Syn., 1870. p. 52. 

 Diplodon celehori Simpson, Syn.. 1900, p. 890. 



Close to varieties of mencieci, but solider and more evenly 

 long rhomboid. The epidermis is darker and thicker than in 

 that species, the median radial impression on the umbonal re- 

 gion is peculiar ; the pseudocardinals in an adult state are 

 stumpy, while in mei!.':ic.ai they are compressed. This species- 

 shows a few well-impressed dorsal scars. 



Diplodon piaen'Sis (Tapperone Canefri). 



Shell short rhomboid, conA'ex, apparently rather thin, inequi- 

 lateral ; beaks but slightlv elevated ; anterior end regularly 

 rounded, a little narrower than the posterior end ; basal and 

 dorsal lines nearly straight ; dorsal slope obliquely subtrun- 

 cate, curving into the dorsal region ; surface densely and del- 

 icately, concentrically striate ; epidermis fuscous-olive ; pseudo- 

 cardinals small, short, subcompressed ; laterals lightly arcu- 

 ate ; nacre flesh-white, iridescent. 



Length 49, height 35, diam. 19 mm. 



Fly River, New- Guinea, 

 Unio Hycnsis Tappf.rone Canefri, Ann. Mus. Genov., XIX, 



1883. p. 293, fig. I. 

 Diplodon flyensis Simpson. Syn.. 1900, p. 890. 



I have never seen this species, but the excellent figures by 

 its author show it to be a Diplodon without doubt and closely 



