588 riini-KKinstis or rin: \ATK>\AI. MISI:I.M. 



" Margarita (Anodonla) exilis LEA, Syn., 1838, p. 32. 



* Anodon ejilis CATLOW and RKKVE, Conch. Xom., 1845, p. 66. 



* Margaron (Anodonta) will* LKA, Syn., 1852, p. 51; 1870, p. 82. 

 Monocondytoa exilis P.-ETEL, Conch. Sam., Ill, 1890, p. 174. 



* Anodonla siliqiia KrsTKH? Conch. Cab. Ano., 1852, p. 57, pi. XIV, tig. 5. 



* Anodonta polila Moussox, L. and Suss. Moll. Java, 1849, p. 98, pi. xix. figs. 2, 3. 



* Moussox, Zeits. fiir Mai., VII, 1851, p. 46. *H. and A. ADAMS, Gen. Kec. 

 Moll., IT, 1857, p. 504. * PJETEL, Conch. Sam., Ill, 1890, p. 183. 

 Margaron (Anodonta) poUta LEA, Syn., 1852, p. 53. 

 " Anodon politnx SOWKKHY. Conch. Icon., XVII, 1867, pi. XII, fig. 36. 



* t Monocondyloa comprcssa LEA, Pr. Ac. N. Sci. Phila., VII, 1863,p. 190; * .11. Ac. 



N. Sci. Phila., VI, 1866, p. 30, pi. xi, fig. 29; * Obs., XI, 1867, p. 34, pi. xi, fig. 

 29. CLESSIX, Conch. Cab. AUG., 1876, p. 258, pi. LXXX, figs. 3, 4. 



* Psendodon comprcssa CONRAD, Am. .11. Conch., I, 1865, p. 233. 



* Jlargaron (Monocondylaa) compressa LEA, Syn., 1870, p. 73. 



* Spatlta compressa P.KTKL, Conch. Sam., Ill, 1890, p. 188. 



* Anodon jarana SOWERBY, Couch. Icon., XVII, 1867, pi. xi, fig. 33. 



* Anodon graciliit SOWERBY? Conch. Icon., XVII, 1867, pi. xiv, fig. 45. 



* Anodon lellettl SOWERBY? Conch. Icon., XVII, 1867, pi. xix, fig. 71. 



*t Anodonta sempervirens DESHAYES, Xouv. Arch, de Mus., X, 1874, p. 120, pi. v, 

 figs. 4, 5. * P^ETEI., Conch. Sam., Ill, 1890, p. 184. 



Southeastern Asia, Sumatra, Java. 



tPILSBRYOCONCHA CARINIFERA Conrad. 



* Anodon ta carl nifera CONRAD, Cover of Monography, No. 9, 1837. 1 TROSCHEL, 



Arch, fiir Naturg., IV, 1838, Pt. 2, p. 288. B. H. WRIGHT, Check List, 1888. 



Southeastern Asia, probably. 



PILSBRYOCONCHA LEMSLEYI Morelet. 



* Anodonta lemslryi MORELET, 3 Ser. Conch., IV, 1875, p. 328, pi. xiv, fig. 1. PyETEL, 



Coi-ch. Sam., Ill, 1890, p. 181. 



Cambodia, Siam. 



PILSBRYOCONCHA SCHOMBURGKI von Martens. 



'Anodonta schombun/ki vox MARTENS, Proc. Zool. Soc. Lond., 1860, p. 15. 

 , Conch. Sam., Ill, 1890, p. 184. 



Siam. 



Genus MEDIONIDUS Simpson, 19OO. 



(Type, Unio conradiciis Lea.) 

 Medionidus SIMPSON, Pr. Ac. N. Sci. Phila., 1900, p. 77. 



Shell elongated, rather inflated, often arcuate when adult, sometimes 

 having a posterior ridge; dorsal slope and occasionally the posterior 



'There is a specimen of Pilzbryoconcha in the Philadelphia Academy which agrees 

 perfectly with Conrad's description, and is probably the type. My attention was 

 called to this by Mr. Pilsbry, who believes this to be the shell Conrad described. It 

 is rather a small species. 



-An old, elongated, rather peculiar shell. Conrad's species may be the young of 

 it, and Morelet believes that Martens' A. schombingki is very close to his shell I 

 have not seen a sufficient amount of material of this genus to determine with cer- 

 tainty whether all these are valid species. 



