PTVCnORHYNCHUS II47 



Group of F^tychorJiynchns apiccllatiim. 



Shell subrhoniboid, more or less biangulate behind 

 Ptvcmoriiynchus APicKLivATiTM (Heude). 



Shell somewhat elongated, subrhoniboid, being a little higher 

 behind than in front, rather solid, convex, inequilateral ; an- 

 terior end rounded; base line nearly straight; dorsal outline 

 lightly curved ; dorsal slope obliquely truncate ; posterior ridge 

 widely, feebly double, ending in a biangulation at and below 

 the median line ; beaks apparently low, plicate sculptured : sur- 

 face with faint, concentric sculpture and with numerous deli- 

 cate plications on the dorsal slope ; epidermis yellowish-black ; 

 pseudocardinals rather solid, striate ; laterals remote, not 

 strongly developed ; nacre brownish-rose. 



Length 60, height 33, diam. 16 mm. 



Torrents of Tche-tcheou fou, province of Ngan-houe, China. 

 Unio apiccllatus Y[f,vt)V., Conch. Fluv. Nank., VIII, 1883, pi. 



i<xiii, fig. T26. 

 Ptychorhynchus apiccllatus Simpson^ Syn., 1900, p. 851. 



Heude states that the beaks of this in a young state are deli- 

 cately plicate sculptured, but whether the plications are zigzag, 

 radial or concentric he does not inform us. 



Ptychorhynchus schomburgianum (Heude). 



Shell elliptic rhomboid, moderately solid, subinflated, in- 

 equilateral ; beaks but slightly elevated ; anterior end narrowed 

 a little, rounded; base line lightly curved; posterior ridge 

 rounded ; dorsal outline somewhat arched ; dorsal slope ob- 

 liquely subtruncate, below the truncation the shell is rather nar- 

 rowly rounded ; surface brownish-black ; dorsal slope having a 

 few faint plications ; pseudocardinals pyramidal, solid, oblique, 

 serrulated ; lateral double in the right valve, obsolete in the left ; 

 muscle scars well marked ; nacre salmon, fuscous, shining, 

 radiately striate, concentrically iridescent. 



Length 52, height 25, diam. 17 mm. 



Isle of Hainan, China. 



