1 2 14 HYRIA 



Some shells are strongly sculptured throughout, while others 

 are partially so or nearly smooth. Some apparently full grown 

 specimens are thin and but little inflated; others are solid and 

 full. 



Hyria rugosissima Sowerby. 



Shell subrhomboid, convex, rather solid, inequilateral, with 

 a nearly straight dorsal line, which is winged before and be- 

 hind ; beaks low, compressed sculptured with very strong, 

 subradial ridges, which curve toward each other and unite 

 below ; the sculpture is carried over the entire shell, being 

 divaricate on the moderately elevated, subangular posterior 

 ridge and often corrugated and subnodulous ; anterior end with 

 a small wing above, rounded and slightly cut away below ; base 

 line curved, fullest behind the middle; posterior end obliquely 

 truncate with a wing and often an incurved outline above ; 

 epidermis greenish-brovvn ; pseudocardinals compressed, some- 

 what split; laterals curved, strong, remote, with the other teeth 

 somewhat vcrticallv striate ; nacre flesh-colored, not mnch 

 thickened in front. 



Length 125, height 80, diam. 38 mm. 



Length 107, height 85, diam. 35 mm. 



Amazon River. 

 Hyria rugosissima SowERBy, Conch. Icon., XVII, 1869, pi. iii, 



fig. 5. — Simpson, Syn., 1900, p. 869. 



Very close to corrugata, but a larger, much more strongly 

 sculptured species. Several specimens of different ages are 

 before me, all of which are heavily sculptured throughout. It 

 is less inflated, as a rule, than corrugata. and the anterior end 

 is a little wider. 



HvKTA LATiALATA Sowerby. 



Shell almost regularly triangular, compressed with a low 

 anterior dorsal wing and a very high triangular posterior one ; 

 posterior ridge subangulate, ending at the base of the shell ; 

 between this point and the hinder base of the wing the shell 

 is almost squarely, subtruncate ; beaks low, their sculpture con- 

 sisting" of rather delicate, subradial ridcrcs, the inner ones of 



