134 unioxiu.t:. 



Subfamily HYRIN^. 



Male and female sliells alike, with beak sculpture radial or 

 zigzag-radial ; niarsupium occupying the inner gills only. 



Disfrihution. Southern and Eastern Asia; Malay Archipelago ; 

 Solomon Islands ; Australia ; New Zealand ; Tasmania ; South 

 America ; and Africa. Several of the genera are found in the 

 Indian Region. 



Genus UNIO. 



Unio, Iletziiis, Diss. p]ist. Test. Gen. 1788, p. IG ; Bruguiere, C'hoix 



de Memoires, i, 1792, p. 106. 

 Limnmt, Poll (pars), Test. utr. Sic. i, 1791, p. 31. 

 Lymnium, Okeii, Lehrbuch, 1815, p. 237. 

 Elliptio, Rafinesque, J. de Phys. et Hist. Xat. 1819, p. 426. 

 Mysca, Tin ton. Conch. Ins. Brit. 1822, p. 243. 

 Canthyria, Swainson, Tr. on Mai. 1840, p. 278. 

 Uniomerits, Conrad, Proc. Acad. Xat. Sci. Philadelphia, vi, 1853, 



p. 268. 



Type, Unio tamklus, Eetzius, from Northern and Central 

 Europe, Siberia. 



Range. Europe, Siheria, Asia Minor, Assyria, N. Africa, and a 

 single species recorded from Kashmir. 



Shell inequilateral, ovate or elongate, generally cuneate, ridged 

 V ith concentric growth-lines ; umbones moderately large, generallv 

 corrugately sculptured ; binge possessing one pseudocardinal and 

 one lateral tooth in the right valve and two pseudocardinals and 

 two laterals in the left valve; umbonal cavity sliallow. 



The following description of the animal is taken from Simpson's 

 work on the Unionidse.* " Animal having the inner branchiae 

 free from the abdominal sac for from one-half to their entire 

 length ; marsupium occupying the whole length of the outer 

 gills only, forming a thick, smooth pad when filled with young ; 

 gills united to the mantle behind to their extreme points, or very 

 nearly so ; papillie on branchial and anal openings unbranched ; 

 superanal opening always closed below." 



Section LYMNIUM. 

 Lymnimn, Oken, Lehrbuch, 1815, p. 237. 



Type, Unio pictormn, ~Retz\ViS; Europe. 



Range. Europe ; X. and C. Asia. 



Oken's description being totally inadequate, it has been ampli- 

 fied by Simpsou as follows : — " Shell generally smooth ; beak 

 sculpture broken, often somewhat corrugated or pustulous ; 



^'" Washington, D.C., Smithsonian Inst. Nat. Miis. Proc. xxii, 1900, p. 680. 



