DIPI.ODON J 267 



one or two faint, radial ridges above it; posterior slope sub- 

 truncate; base angularly niHated near the hinder end of the 

 . shell, the posterior point of which is faintly biangulate and on 

 he median line; surface with delicate, close, raised growth 

 ines; epidermis nearly black, lighter at the umbonal region- 

 le t valve with one lamellar pseudocardinal with somehmes 

 a burred vestige of a posterior one, and two delicate laterals- 

 right valve with two long pseudocardinals and one lateral' 

 beak cavities shallow ; nacre bluish, silvery. 

 Length 57, height 29, diam. 17 mm. 

 Rio Macacon, Rio Janiero, Brazil; xNew Granada 



Fhila 111, 1858, p. 303, pi. XXVIII, fig. 20.-KUST1.R, Conch 

 Cab. Unio, 1862, p. 2QO d1 xriT fio- ^ c youcn. 



Iron V\'T rQrJ , f ' ^^ 6-— SovVlJRBY, Conch. 



icon., XVI, 1808, pi. xc, fig. 485. 

 Margaron (Unw) dimkenanus Ua, Syn., 1870 p .. 

 Dtplodon atratns (part), Simpson, Syn., 1900, p! 88. 



Lea has two specimens in his collection, one from Dr Dtm- 

 ker, said to some from Rio Janiero, and the other which L 

 has figured from New Granad., presented by Verreatr Th v 



Tar^ttf r '"T'' ^"' ''''-' ^° '-^- distinguishtg 

 characters the angular post-basal swelling, the o-]ossv black 



DfPumoN BiNNEvi (Lea). 



Shell long elliptical, pointed on the median line behind with 

 he posterior base sontewhat angularly swollen and the pos- 

 er,or slope snb.runcated. subcompressed, thin : posterior ndge 



low sub-b,angulate; beaks low and somewhat compressed 



eroded in the onlv specimen seen b,„ =l,„ ■ ,■ • ' ^™' 

 srnlnf„r. , ,•■ l^ ™" '''"^"' ""^ showmg distinct, radial 

 sculpture extending some distance out on to the disk: surface 

 irregularly, concentrically scnlptured: epidermis olive or 

 bronzy-green, scarcely shining: left valve with an anterior 

 ompresse pseud^ardinal. the bintler one a mere low tube™ 

 and tuo delicate laterals: right valve with two compressed 



