580 PROCEEDINGS OF THE XATIOXAL MUSEUM. 



tHYRIOPSIS DELAPORTEI Crosse and Fischer. 



* Unio (Arconaia) deJaportei CROSSE and FISCHER, J. de Conch., XXVI, 1876, p. 



327, pi. x, fig. 1; xi, fig. 5.' 



Cambodia; Siam. 



(Group of 7///r/o/>.s/.v myersianus.) 



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

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

 faint, irregular ridges, sometimes slightly nodulous. 



tHYRIOPSIS MYERSIANUS Lea. 



*Unio myersianiis LEA, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 92; *J1. Ac. N. Sci. 

 Phila., Ill, 1857, p. 290, pi. xxn, fig. 2 ; * Obs., VI, 1857, p. 10, pi. xxn, fig. 2. 

 " SOWERBY, Conch. Icon., XVI, 1866, pi. L, fig. 265. *MORELET, Ser. Conch., 

 IV, 1875, p. 344. *P.ETEL, Couch. Sam., Ill, 1890, p. 160. 



*Maryaron ( 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. xxin, fig. 3; *Obs., VI, 1857, p. 11, pi. xxm, fig. 3. 

 * VON MAKTENS, Pr. Zool. Soc. Lond., 1860, p. 14. * SOWERBY, Conch. 

 Icon., XVI, 1866, pi. XLVIII, fig. 260. * P^TEL, Conch. Sam., Ill, 1890, p. 155. 

 *Maryaron ( Unio) hotisei LEA, Syn., 1870, p. 28. 



Siarn; Cambodia. 



HYRIOPSIS SUTRANGENSIS L. Morlet. 



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

 Sutrang River, Siam. 



HYRIOPSIS PINCHONIANUS Heude. 



*Unio pinchonianiis HEUDE, Conch. Fluv. Nank, VIII, 1883, pi. LXIII, tig. 12. 

 P^TEL, 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 subtriyonus SOWERBY, Couch. Icon., XVI, 1867, pi. LVIII, fig. 292. - 



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

 *Maryaron ( Unio) snblrigonus LEA, Syn., 1870, p. 28. 



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

 not twjsted. 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 snbtriyonu* in the Couchologia, the name 

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

 l(ea) cambojensiz, believing it to be the same as Petit's Pseiidodoti rambojcnsis. It 

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

 tsianus, and accept his name for it. 



