NO. 1205. SYNOPSIS OF THE NAIADES—SIMPSOX. 851 



somewhat blurred granulous laterals j right valve with a single bluut 

 pseudocardinal, the hiuge line in front of it being excavated, and a 

 curious blurred lateral which is sometimes slightly split up; beak cav- 

 ities shallow; dorsal scars few ; nacre whitish. Animal unknown. 



(Group of Pti/chobranchus pjisteri.) 

 Characters as in the genus. 



fPTCHORHYNCHUS PFISTERI Heude. 



*' Unio i^fisteri Heude, Jl. de Conct., XXII, 1874, p. 112; *' Conch. Fluv. Nauk., I, 

 1875, pi. 1, fig. 1.—" P.ETEL, Conch. Sam., Ill, 1890, p. 163. 



PTYCHORHYNCHUS PFISTERI var. INSPIRATUS Heude. 



^ Unio j^fisterivar. iitspiratiis Heude, Conch. Fluv. Nauk., II, 1877, pi. xiv, fig. 28. — • 

 *PvETEL, Conch. Sam., Ill, 1890, p. 155. 



iSankin River, China. 



t PTYCHORHYNCHUS MEDIASTINUS Heude. i 



* Unio mediasiinus Heude, Conch. Fluv. Nank., VIII, 1883, pi. LXiii, fig. 123. — 



*'P.ETEL, Conch. Sam., Ill, 1890, p. 158. 



China. 



(Group of Ptychorhynchvs apicellatns.) , 



Shell subrhomboid, more or less biangulate behind. 



PTYCHORHYNCHUS APICELLATUS Heude. 



"" Unio apicellatns Heudk, Conch. Fluv. Nank., VIII, 1883, pi. LXiii, fig. 126. 



China. 



PTYCHORHYNCHUS SCHOMBURGIANUS Heude. 



* Unio scliomburfjianus Heude, Jl. de Couch., XL, p. 314; " Conch. Fluv. Nank., IX, 



1885, pi. Lxxii, fig. 139.—* P.ETEL, Conch. Sam., Ill, 1890, p. 167. 



Isle of Hainan, China. 



PTYCHORHYNCHUS INCERTUS Simpson. 



* Unio compressus Heude,- Couch. Fluv. Nank., Ill, 1877, pi. xxiv, fig. 52. — 



* Pjstel, Conch. Sam., Ill, 1890, p. 148. 



* Unio murinus Heude, Conch. Fluv. Nauk., VIII, 1883, pi. lxii, fig. 121. 

 ^ Unio morinus P^etel, Conch. Sam., Ill, 1890, p. 160. 



China. 



Genus VIRGUS, Simpson, 1900. 

 (Type, Unio heccarianiis Tapperone Canefri.) 



Shell rather solid, elongated, inequilateral, compressed, rounded in 

 front, nearly straight below, the dorsal line as far back as the hinder 



' Probably ojly a variety of P. pfisteri. 



2 The name conqiressus has been twice used previously for a Unio. I change it here 

 to incertus. 



