SYNOPSIS OF THE NAIADES SIMPsa\. 587 



and one lateral, which is reflexed upward; epidermis folded into the 

 hinge, and scaly; a single dorsal scar on the inner side of each hinge 

 plate; muscle scars united ; palleal line distinct ; beak cavities large and 

 wide; nacre very dull. Animal unknown. 



tLEPIDODISMA LANGUILATI Heude. 



'* Unio languilati HEUDE, J.de Conch., XXII, 1874, p. 116; * Conch. Flnv. Nank., 



I, 1875, pi. vii. P.ETEL, Conch. Sam., Ill, 1890, p. 156. 



' Lepidodesma languilati SIMPSON, Pr. U. S. Nat. Mus., XVIII, 1896, p. 311. 



* Cristaria megadesma VON MARTENS, S. B. Nat. Fr., 1875, p. 3; * Mai. Bl., XXII, 



1875, p. 187; * Nov. Conch., IV, 1876, p. 152, pi. cxxxv, fig. 1. 



* Barbula megadesma P.ETEL, Conoh. Sam., Ill, 1890, p. 175. 



China. 



LEPIDODESMA ALIGERA Heude. 



* Unio languilatus var. aligerus HEUDE, Conch. Flnv. Nank., Ill, 1877, pi. xvn, 



fig. 37. *P.KTEI., Conch. Sam., Ill, 1890, p. 156. 



* Lepidodesma aligera SIMPSON, Pr. U. S. Nat. Mus., XVIII, 189H, p. 311. 



China. 



Genus PILSBRYOCONCHA Simpson, 19OO. 

 (Type, Anodonta ejrilis Lea.) 



Shell elongated, elliptical, compressed, thin, with a low, posterior 

 wing, narrow and rounded in front, nearly straight below, expanded at 

 the post-basal region, pointed behind. Beaks compressed, sculptured 

 with several coarse, low, irregularly concentric undulations, often 

 slightly doubly looped ; surface nearly smooth, shining, yellowish to 

 ashy brownish, sometimes showing very faint rays; hinge straight or 

 slightly curved, reduced to a mere line, often showing a faint, com- 

 pressed, smooth tooth in front of the beaks, otherwise edentulous; 

 nacre brilliant, silvery and iridescent; muscle scars faint. Animal 

 pure milky white; lobes of the mantle united behind into two short 

 siphons. ' 



t PILSBRYOCONCHA LINGUvEFORMIS Morelet. 



* Anodonta Ungua>formis MORELET, Ser. Conch., IV, 1875, p. 329. pi. xiv, fig. 5. 



* P^ETEL, Conch. Sam., Ill, 1890, p. 181. 



* Margaron ( Unio) linguaformig LEA, Syn., 1870, p. 48. 



Siam; Cambodia". 



t PILSBRYOCONCHA EXILIS Lea. 



* Anodonta exilis LEA, Tr. Am. Phil. Soc., VI, 1839, p. 81, pi. xxn, fig. 68; *Obs., 



II, 1838, p. 81, pi. xxn, fig. 68.* TROSCHEL, Arch, fiir Natnrg., V, 1839, Pt. 2, 

 p. 239. * HAN-LEY, Test. Moll., 1842, p. 224; *- Biv. Shells, 1843, p. 224. 

 "* H. and A. ADAMS, Gen. Kec. Moll., II, 1857, p. 503. * MORELET, Ser. Conch., 

 IV, 1875, p. 327. * CLESSIN, Conch. Cab. Auo., 1875, p. 171, pi. LVI, figs. 

 6-8. * PJETEL, Conch. Sain., Ill, 1890, p. 179. 



'According to Deshayes, .11. de Couch., 1875, pp. 81-85. He does not give any other 

 characters of the soft parts. 



