DIPI.ODON 1245 



Unio piceus Li-a, Pr. Ac. N. Sci. Phila., IV, i860, p. 91 ; Jl. 



Ac. N. Sci. Phila., V, 1863, p. 397, pi. xu, fig. 287; Obs., X, 



1863, p. 15, pi. xi.i, fig-. 287. 

 Mar^^aron (Unio) Picens Lua, Syn., 1870, p. 53. 

 Diplodon piceiis Simpson, Syn., 1900, p. 877. 



"Three specimens. They all dififer slightly in the ellipticity 

 of outline. One being a little wider and the other not quite 

 so much so as that figured. It is very near to liigubris (nobis) 

 in outline and in the blackness of the epidermis, but in the 

 nacre it differs entirely, as it does in the cardinal teeth. It is 

 also very near in outline to lepidus, herein described. The 

 single cardinal tooth in the left valve is very unusual. The 

 blackness of the epidermis is very striking and apparently it 

 is without rays. In looking through the valve the hue is 

 greenish, and one of the specimens exhibits obscure rays. The 

 beaks of all the three are eroded, and I cannot therefore de- 

 scribe the undulations of the tips. From indications in the 

 exposed nacre I have no doubt that this species has diverging 

 undulations at the tips. The transverse striae are coarse, al- 

 most amounting to sulcations. The cardinals are nearly on 

 the same curve with the lateral teeth." 



DiPivonoN supposiTus n. s. 



Shell oblong, elliptical or subrhomboid, subcompressed, sub- 

 solid ; posterior ridge nearly or entirely wanting ; beaks rather 

 low, their sculpture consisting of a number of short, straight, 

 radial bars ; surface with numerous fine growth lines ; epider- 

 mis olive or brownish, bronzy, generally shining ; left valve 

 with two compressed pseudocardinals and twO' laterals ; right 

 valve with two pseudocardinals, the upper small, and one lat- 

 eral, teeth all delicate ; nacre bluish-white, thickened a little, 

 in front. 



Length 50, height 26, diam. 14 mm. 



Length 55, height 32, diam. 19 mm. 



Southern Brazil, numerous localities. 

 Diplodon piceus (part), Simp.son, Syn., 1900, p. 877. 



A form with few decided characters, yet one which does not 

 •seem to quite equal any other. The young are often brilliant 



