868 PBOCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



Genus HYRIA Lamarck, 1819. 



(Type, Syria corrugata Lamarck.) 



Hyria Lamarck, An. sans Vert., VI, 1819, p. 81.' 

 Triplodon Spix, Test. FIut. Bras., 1827, p. 35. 

 Naia Swainson, Tr. on Mai., 1840, p. 379. 



Shell subrhomboidal, solid, slightly inflated, narrower and dorsally 

 winged in front, and having a post-dorsal wing; posterior ridge often 

 double, causing the shell to be biangulate behind; beaks low, with 

 strong, nearly radial sculpture, the central bars coalescing below, the 

 whole continuing as strong, radial, and zigzag ridges over more or less 

 of the disk; epidermis thick, greenish when young, brownish or black- 

 ish when old ; there are two or more rather short, compressed pseudo- 

 cardinals in each valve, which are much split up into denticles; one 

 lateral in the right and two in the left valve; teeth often somewhat 

 vertically striated ; dorsal scars numerous; nacre whitish. 



Animal with mantle lobes united together behind and furnished with 

 two short, contractile siphons. (J. E. Gray.) 



Subgenus HYRIA Lamarck, 1819. 

 (Type, Hyria corrugata Lamarck.) 

 Characters as in the genus. 



t HYRIA CORRUGATA Lamarck. 



* Hyria corrugata Lamarck, An. sans Vert., VI, 1819, p. 82. — * Sowerby, Rec. and 



Foss. Shells, 1823, No. XVI, fig. d ; * Conch. Man., 1839, fig. 144.— * Reeve, 

 Conch. Syst., I, 1841, p. 120, pi. xc, fig. 2.—* Hanley, Test. Moll., 1842, p. 215; 



* BiT. Shells, 1843, p. 215.—* Catlow and Reeve, Conch. Norn., 1845, p. 65.— 



* KuSTER, Conch. Cab. Unio, 1856, p. 140, pi. xli, fig. 1.—*' Chenu, Man., 1859, 

 II, p. 149, fig. 733.—* Reeve, Elem. Conch., II, 1860, pi. xxxi, fig. 179.—* Sow- 

 erby, Conch. Icon., XVII, 1869, pi. i, fig. 1.— *P.etel, Conch. Sam., Ill, 1890, 

 p. 189. 



* ? Unio corrugata Blainvijlle, Man., 1825, p. -539, pi. lxvii, fig. 1. 



^In 1753 Klein (Testamen Method!, p. 135, pi. 9, fig. 36) used the name Triquctra 

 for the shell which has since been known as Hyria syrmatophora GTonovins. In 

 1817 Schumacher founded the genus Prisodon (Essai Nouv. Systeme, p. 138), in 

 which under section a he placed his P. ohliquus, a smooth species considerably 

 drawn out, and in section h he put P. truncatiis, which is possibly the same as the 

 Castalia amhigua of Lamarck. These certainly belong to two genera. Dr. Lea in the 

 Synopsis used Klein's name for the winged shell {Hyria corrugata Lamarck), and used 

 the name Prisodow for Schumacher's section h (P. truncatus Scliumaclier) . Lea erred in 

 this, because Klein was not a binomial author, and his name-can not be used. In the 

 proceedings of the U. S. National Museum, XVIII, 1896, p. 315, I restored the name 

 of Prisodon Schumacher to the first section, pointing out that the P. obliquus Schu- 

 macher must stand as its type. Two years after Schumacher's name appeared 

 Lamarck published the generic name Hyria in the Animaux sans Vertebres, VI, 1819, 

 p. 81, and placed in it first his H. avicularis, which equals Schumacher's P. obliquus, 

 and secondly H. corrugata. I now believe that these corrugated forms are generically 

 distinct from the smooth ones, and as Schumacher's Paxyodon is almost certainly 

 founded on one of the smooth species, Lamarck's name Hyria can be used by elimi- 

 nation for the corrugatus and allied forms. 



