DIPLODON 126-^ 



Unio obtusa d'ORmcNY, Guer. Mag., 1835. p. 35 ; \'oy. Am. 



Mer., 1843, P- 610. 

 Diplodon obfiisus Simpson, Syn., 1900, p. 882. 



'•This species is close to U. patagonica, but is distinguished 

 by its much larger size, more obtuse extremities and by its 

 more rugose surface." 



Said by d'Orbigny to be of Ferussac, but he does not say 

 where that author described it and I do not know where. If 

 the species be a valid one. it will probably have to have a new 

 name. d'Orbigny did not describe it until 1843. I" 1835 he 

 quotes it as "obtusa Fer.," but gives no description and refers 

 it to depressa Less., (1830), from New South Wales. The 

 obtusa. (Fer.) d'Orbigny of 1835 would fairly seem to be a 

 synonym of dchrcssa and the name could not be used again for 

 the Chilean species when finally described in 1843. l^^ntil the 

 status of the species is definitely determined, it hardlv seems 

 M'orth while to rename it. 



Diplodon khuaconicus (Kuster). 



Shell subrhomboid, a little wider behind, convex, inequilat- 

 eral with only moderately full beaks, whose sculpture consists 

 of strong, radial bars extending well onto the disk ; posterior 

 ridge somewhat double, ending behind in a feeble biangula- 

 tion just below the median line; surface densely, concentric- 

 ally striate and sulcate ; epidermis very dark, showing the 

 growth lines; pseudocardinals compressed, the posterior one 

 in the left valve imperfect ; nacre bluish-white. 



Length 53, height 30, diam. 16 mm. 



Uruguay. 



Brazil. 



Unio rhuaconiciis Kuster, Conch. Cab. L'nio, 1856, p. 145, pL 



xui, fig. 5. 

 Diplodon rhuaconicus Simpson, Syn., 1900, p. 882. 



This is very difii'erent from d'Orbigny's rhuacoica. 



Kuster states that this is Unio rhuaconicus Pfeififer teste 

 Charpentier. I know nothing of it bevond the figure and 



