t^^l

184 TJNIONID.I;.
double in the right; lateral teeth long, thin, bladed and nearly
straight; anterior cicatrices distinct; posterior cicatrices coniluent;
dorsal cicatrices situated nearly in the centre of the cavity of the
beaks ; cavity of the beaks exceedingly shallow ; nacre pearly
white and iridescent It closely resembles the U. marginalis
of Lamarck, but differs from that species in being more
transverse, in the beaks being more retuse, in the dorsal line
being nearly straight, and in its not being possessed of a light
border along the margin. The cardinal teeth are remarkably thin,
and form nearly a line with the lateral teeth."
Subsp. generosus {Gould).
JJnio r/enerosus, Gould, Proo. Boston Soc. jSTat. Hist, ii, 1847,
p. 220; Otia Conch. 1862, p. 210; H. & T., 0. I. 1876, p. 22,
pi. 46, fig. 4 ; Pajtel, Conch. Sam. iii, 1890, p. 153.
Margaron (Unio) generosus, Lea, Syn. 1870, p. 29.
? TInio Imnellatzis, Soiverby, Ooach. Icon, xvi, 1868, pi. 94, Jig. 511.
Lamellidens generosus (Gould), Simpson, Washington, D.C., Smiths.
Inst., Nat. Mus. Proc. xxii, 1900, p. 867.
Original description:—Testa magna, solida, transversa, oblongoovata,
inequilaterali, antice rotundata et angustata ; postice obliquata,
subrostrata, ad apicem truncata; margine veiitrali arcuata,
dorsali recta, abscendente; umbonibus contiguis haud elevatis ;
valvis subtumidis radiatim substriatis, postice subcostatis, epidermide
fuliginosa, disco nitido: dentibus remotis; cardinalibus
elongatis, obliquis, laminatis : margarita alba vel salmonacea
limbo irideseente.
Long. 64, lat. 95-5, diam, 38-25 mm.
Hob. Newville, Tavoy {Mrs. Vinton); specimens in the Indian
Museum are labelled respectively Myadong, Upper Burma
{Anderson), Mandalay {Annandale), and Bhamo {J. Coggin
Brown).
Subsp. jenkinsianus {Benson).
Unio jenkinsianus, Benson, A. M. N. II, x, 1862, p. 185; II. & T,,
C. I. 1876, p. 19, pi. 41, fig. 4; Paitel, Conch. Sam. iii, 1890,
p. 155.
Lamellidens jenkinsianus (Benson), Simpson, Washington, D.C.,
Smiths. Inst., Nat. Mus. Proc. sxii, 1900, p. 857.
Original description:—Testa transverse elongata, subacuminatoovata,
valde insqquiiaterali, tumida, crassa, antice brevi rotundata,
postice elongata, mininie alata, superne sensim descendente,
demum angusta, obtusa; margine basali antice convexiusculo,
postice subrecto, ligamento brevi; disco valde tumido, transverse
plicate; epidermide picea, versus marginem ventralem olivacea;
umbonibus leviter convexis, decorticatis, apicibus obtusis ; dentibus
arcuatim sitis, crassiusculis, erosis, cardinalibus elongatiusculis,