1912.] H. B. Preston: The Asiatic Natades. 293 
different texture of the shells, it is somewhat difficult to under- 
stand his reasons for so placing them. 
43. Nodularia (Nodularia) nuttalliana (Lea), Simpson, 
Syn. Naiades, Proc. U.S. Nat. Mus., XXII, p. 817,=Unio nuttal- 
lianus, Lea, Proc. Ac. Nat: Sci., Philad., VIII, 1856, p. 103; Obs., 
WVii1857, p.,30;, pli xxx, fig. 254 Jl Ae Natisei.) Philad: 1858, 
Ser? 2) Ill; pi 310; pli xxx, fig. 25; Hanley and The@bald, 
Conch. Ind., p. 1g, pl. xli, figs 5, 6,—Margaron (Umo) nuttallia- 
nus Wea, Sym.,1870, p. 74. 
Assam, Reg. No. 2229; Cachar, Reg. No. #158. 
44. Nodularia (Nodularia) involuta (Benson), Simpson, 
Syn. Naiades, Proc. U.S. Nat. Mus., XXII, p. 817,—Umio involu- 
tus, (Benson), Hanley, Rec. Biv. Shells, 1856, p. 385, pl. xxiii, 
fig. 19; Hanley and Theobald, Conch. Ind., p. 19, pl. xii, fig. 2. 
Sylhet, Reg. No. 5287. 
Sec. RADIATULA, Simpson, 1900. 
45. Nodularia (Radiatula) crispisulcata (Benson), Simp- 
son, Syn. Naiades, Proc. U.S. Nat. Mus., XXII, p. 820,=Umto crts- 
pisulcatus, Lea, Ann. Mag. Nat. Hist., X, 1862, p. 193; Sowerby, 
Conch. Icon., XVI, 1866, pl. xlix, fig. 262,—Margaron (Unio) 
crishisulcatus, Lea, Syn., 1870, p. 149. 
Irrawaddy near Thayetmyo (Asiatic Society of Bongal), Reg. 
INo7 2257 Pee ()). Anderson), Reg. No. 2712; Pesu, Reg. No. 2142 ; 
Regu, Reg: No. £22, 
46. Nodularia (Radiatula) lima, Simpson, Syn. Naiades, 
Proc. U.S. Nat. Mus., XXII, p. 820,=Unio raduia (Benson), 
Hanley, Rec. Biv. Shells, Supp., 1856, p. 382, pl. xxiii, fig. 41; 
Hanley and Theobald, Conch. Ind., p. 5, pl. x, fig. 3,==Dysonomia 
vadula, Rochebrune, Bull. Soc. Phil., VI, 1882, p. 42. 
Siliguri, N. Bengal, Rez. Nos. 2589, 4725, 3862; Sikkim, Reg. 
No. 2426. 
46a. Var. siliguriensis, Preston, =Unzio siliguriensis, Preston, 
nec: Ind? Mus:- Calcutta, Ti Pt: a, -pi47. 
Siliguri, Reg. No. *°2°.  [Type.] 
Having now had an opportunity of examining a good series of 
N. lima, a shell which had previously been inaccessible to me, I 
have no hesitation in reducing U. siliguviensis to a variety of that 
species. 
Gen. Physunio, Simpson, 1900. 
Sec. PHYSUNIO, Simpson, 1900. 
47. Physunio (Physunio) gravidus (Lea), Simpson, Syn. _ 
Naiades, Proc. U.S. Nat. Mus., XXII, p. 830,=Unio gravidus, 
Lea, Proc. Ac. Nat. Sci.; Philad., VIII, 1856, p. 93; Obs., VI, 
£657);-07.02. pl, xaiv, fig. 5° Jl..Ac. Nat Sci ePhilad.,, vet 1656, 
p. 292, pl. xxiv, fig. 5,=Margaron (Unto) gravidus, Lea, Syn., 
1870, p. 28,—Lampsilis gravidus, Rochebrune, Bull, Soc. Phil, VI, 
