t^^l

134 UNioxii)^.
Subfamily HYRIN^.
Male and female sliells alike, with beak sculpture radial or
zigzag-radial; marsupium occupying the inner gills onl)'.
Distribution. 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 Eegion.
Genus UNIO.
Unio, Hetzius, Diss. Hist. Test. Gen. 1788, p. 10 ; Brugiiiere, Choix
de Memoires, i, 1792, p. 106.
Limncea, Poli (pars). Test. iitr. Sic. i, 1791, p. 31.
Lymnium, Oken, Lehrbucli, 1815, p. 237.
Elliptio, Rafinesque, J. de Phys. et Hist. Kat. 1819, p. 426.
Mysca, Turton, Conch. Ins. Brit. 1822, p. 243.
Canthyria, Swainson, Tr. on Mai. 1840, p. 278.
Uniomsrus, Conrad, Proc. Acad. Nat. Bci. Philadelphia, vi, 1853,
p. 268.
TYPE, Unio tumidus, Eetzius, from Northern and Central
Europe, Siberia.
Banye. Europe, Siberia, 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, generally
corrugately sculptured ; hinge possessing one pseudocardinal and
one lateral tooth in the right valve and two pseudocardinals and
two laterals in the left valve ; urabonal cavity shallow.
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; papilla; on branchial and anal openings unbranched;
superanal opening always closed below."
Section LYMNIUM.
Lymnium, Oken, Lehrbiich, 1815, p. 287.
TYPE, Unio pictoriim, Eetzius ; Europe.
Bange. Europe ; N. and C. Asia.
Oken's description being totally inadequate, it has been amplified
by Simpson as follows :—" Shell generally smooth ; beak
sculpture brok3n, often somewhat corrugated or pustulous;
Washington, D.O., Smithsonian Inst. Nat. Mug. Troc. xxii, 1900, p. 680.