DIPI.ODON 1269 



surface is strongly, concentrically sculptured, and the epider- 

 mis is shining", and is a rich bronzy, olivaceous-yellow. Kuster 

 supposes this to be the Uuio auratus of Swainson and Philippi, 

 which is quite a different thing. I therefore give it a new 

 name. 



DiPLODON coKiACEus (Dunker). 



• Shell oval, subrhomboid, subcompressed, surface mostly 

 coriaceous, granulose ; epidermis olivaceous ; anterior end 

 short ; posterior end produced ; beaks small ; nacre bluish-white,, 

 opaque. 



Length 100, height 60, diam. 35 mm. ? 



Rio Negro, Province of Rio Janeiro, Brazil. 

 Unio coriaccus Dunki:r, Zeits. fiir Mai., V, 1848, p. 181. 

 Diplodon coriaceus Simpson, vSyn., 1900, p. 883. 



T know nothing whatever of this species save the descrip- 

 tion and a few remarks in Latin given by its author. Von 

 Thering mentions it in a list as from the Rio Negro in southern 

 Brazil. 



D1P1.0DON CHiLDRjiNi (Gray). 



Shell irregularly elliptical, being slightly curved on the dor- 

 sal line and much more strongly curved below, inequilateral, 

 apparently little inflated and rather thin; beaks moderately 

 full, eroded in the specimen figured; posterior ridge low, 

 rounded, ending behind in a rounded point above the centre 

 of the base; from this point upward the posterior end of the 

 shell is somewhat truncated ; surface showing the rest periods, 

 dark reddish-brown ; teeth compressed ; nacre apparently blu- 

 ish-white. 



Length 74, height 47 mm. 



South America. 

 Unio childreni Gray, Griff. Cuv., XH, 1834, p. 600 f index), 



pi. XX, fig. I. 

 Margarita (Unio) childreni Lea, Syn., 1836, p. 25; 1838, p. 19. 

 Mari^aron (Unio) childreni Lea, Syn.. 1852. p. 28; 1870, p. 44. 

 Diplodon childreni Simpson, Syn., 1900, p. 883. 



