IIIRRINC.Er.LA 1395 



mens obtained since, he considered the two distinct. This 

 species has a more elongated outline, and is decidedly sculp- 

 tured, while Lea's shell is smooth. 



Group of Iheringella rotundata. 



Shell somewhat rounded, sublenticular, posterior ridge rath- 

 er low. 



IlIERINGRLI^A ROTUNDATA (MoUSSOn). 



Shell short elliptical, inflated, rather solid, inequilateral ; 

 beaks full and elevated, somewhat turned forward ; posterior 

 ridge narrowly rounded; surface with concentric striae; epi- 

 dermis olivaceous-fuscous, teeth short, thick, single in each 

 valve, sulcate ; beak cavities deep ; nacre whitish, pearly ; mus- 

 cle scars moderate, subtriangular. 



Length 52, height 42, diam. 30 mm. 



South America. 

 Plagiodon rotundatns Mou.sson, Mai. Bl., XV'I, 1869, p. 187. 



— Pfkii^fer, Nov. Conch., IV, 1876, p. 139, pi. cxxxi, figs. 



8. 9. 

 Iheringella rotundata Simpson, Syn., 1900, p. 913. 



The outline of the shell of this species is almost regularly 

 short elliptical, there being a very blunt point at the ending of 

 the posterior ridge. I have seen young shells in the collection 

 of Mr. H. E. Sargent, which I refer to this species. 



Iheringella p.ai.zanl (von Ihering). 



Shell irregularly subtriangular, solid, subinfiated, having a 

 much greater diameter behind the beaks, inequilateral ; beaks 

 full and high ; anterior end narrowed, rounded ; hinge line very 

 slightly curved, but much higher behind ; posterior end ob- 

 liquely truncate ; base rounded ; epidermis thick, interruptedly 

 radiate, blackish or olivaceous-fuscous ; nacre white, iridescent ; 

 teeth thick, transverse, compressed, double in each valve ; pris- 

 matic border wide. 



Length 86, height 66, diam. 40 mm. 



Rio Paraguay ; San Paulo, Brazil. 



