580 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



jHYRIOPSIS DELAPORTEI Crosse and Fischer. 



^Unio (Arconaia) delaportei Crosse and Fischer, J. de Conch., XXVI, 1876, p. 

 327, pi. X, fig. 1; XI, fig. 5.' 



Cambodia; Siam. 



(Group of Hyriopsis my er. nanus.) 



Shell rather solid, thickened in front; posterior ridge rather low; 

 beaks comiDressed, the sculpture consisting, apparently, of a few rather 

 faint, irregular ridges, sometimes slightly nodulous. 



tHYRIOPSIS MYERSIANUS Lea. 



*Unio myersianus Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 92; *J1. Ac. N. Sci. 

 Phila., Ill, 1857, p. 290, pL xxii, fig. 2; 'Obs., VI, 1857, p. 10, pi. xxii, fig.2.— 

 *SowERBY, Conch. Icon., XVI, 1866, pi. l, fig. 265.— *Morelet, Ser. Conch., 

 IV, 1875, p. 344.— *P^TEL, Conch. Sam., Ill, 1890, p. 160. 



" Margaron ( Unio) myersianus Lea, Syn., 1870, p. 28. 



* t Unio housei Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 92; * Jl. Ac. N. Sci. Phila., 



Ill, 1858, p. 291, pi. xxiii, fig. 3; ^ Obs., VI, 1857, p. 11, pi. xxiii, fig. 3.— 

 *V0N Martens, Pr. Zool. Soc. Lond., 1860, x>- H- — *Sowerby, Conch. 

 Icon., XVI, 1866, pi. XLViii, fig. 260.- ^ P^tel, Couch. Sam., Ill, 1890, p. 155. 

 ^Margaron ( Unio) housei Lea, Syn., 1870, p. 28. 



Siam; Cambodia. 



HYRIOPSIS SUTRANGENSIS L. Morlet. 



* Unio sutrangensis L. Morlet, Jl. de Conch., XXXVII, 1889, p. 195, pi. ix, fig. 3. 

 Sutrang Eiver, Siam. 



HYRIOPSIS PINCHONIANUS Heude. 



*Unio pinchonianus Heude, Conch. Fluv. Nank, VIII, 1883, pi. lxhi, fig. 12. — 

 PyETEL, Conch. Sam., Ill, 1890, p. 163. 



China. 



(Group of Hyriopsis vagulus.) 



Shell elliptical, with a rather high, posterior wing, moderately solid, 

 with two slight posterior ridges and a sulcus above them at the junc- 

 ture of the wing. 



HYRIOPSIS VAGULUS Fischer.^ 



* Unio subtrigonus Sowerby, Conch. Icon., XVI, 1867, pi. l\iii, fig. 292. — " P^tel, 



Conch. Sam., Ill, 1890, p. 169 

 *Margaron ( Unio) subtrigonus Lea, Syn., 1870, p. 28. 



' The ventral line of this shell is crooked, having a couple of curves in it, but it is 

 not twisted. Its authors believed Arconaia to be only a section of Unio, and that 

 the animal was essentially like that of that genus. 



-Sowerby published this species as Unio subtrigonus in the Conchologia, the name 

 being preoccupied by Desbayes. In the errata he changed it to Unio (Monocondy- 

 Icea) cambojensis, believing it to be the same as Petit's Pseudodon camhojensis. It 

 certainly is not that shell, and I agree with Fischer that it is near to the Unio myer- 

 sianus, and accept his name for it. 



