LAMELLIDBXS. 183 



"well in other respects ; juvenile specimens are bright brownish- 

 green, older ones blackish ; the following are the measurements 

 of a series at various stages of growth : — 



Lat 



Long, (from umboues) . . 

 Long, (from posterior ex- 

 tremity of wing) .... 

 Diam 



The wings average two-thirds of the length. The lower margin 

 in yi^^iiig spec'nnens is fairlv sti'aight in the middle, in older ones 

 slightly curved inward. The edge running backwards from the 

 innbones, separating the posterior from the lateral surface, is 

 always distinct. The hinge-teeth are nodulated, but comparatively 

 small. 



Uab. The Chindwin ]{i\er, near Kalewa ; also in the liiver Tu, 

 one of the tributaries of the former. 



Young specimens of this variety, in outward form, greatly 

 resemble the if. marginalis var. anodontinus of the ' Conch. lud.', 

 pi. 42, fig. 7. 



Subsp. corrianus (Lea). 



Unio cori-innus, Lea, Philadelphia, Pa., Trans. Amer. Phil. Soc. v, 

 ser. 2, 1834, p. Go, pi. 9, tig. 25; Obs. Genus Unio, i, 1834, 

 p. 177, pi. 9, %. 25; Hanlev, Test. Moll. 1842, p. 207; Biv. 

 Shells, 1843, p. 207, pi. xx, iig. 60 ; Catlow & Reeve, Concli. 

 Norn. 184.5, p. 57 ; H. & A. Adams, Gen. liec. Moll, ii, 1857, 

 p. 491 ; P;T3tel, Conch. Sam. iii, 1890, p. 149. 



Maiyarita (Unio) corrianus. Lea, Syu. 1836, p. 38; 1838, p. 25. 



Mar(jaro)i (Unio) corrianus, Lea, Syxi. 1852, p. 38 ; 1870, p. 61. 



LanieUidens corrianus (Lea), Simpson, AVasliington, D.C, Smiths. 

 Inst., Nat. Mus. Proc. xxii, 1900, p. 857. 



Orifjiiial description : — Shell narrow-elliptical, very transverse, 

 very inequilaterah subangular behind ; valves very thin ; beaks 

 scarcely prominent ; cardinal teeth thin and bladed ; lateral teeth 

 long, thin and nearly straight ; nacre pearly white and iridescent. 



Long. 2.")-o, lat. 53*5, diam. 13*5 n\m. 



Hab. Calcutta. The following localities refer to specimens 

 in the Indian Museum : — Seebsaugor (Peal) ; Pegu ( W. T. Blaa- 

 ford) ; Balagunga, Central Sylhet ; Madras ; 13erliampur, Mur- 

 shidabad District, Bengal ('S". W. Kemp) ; Sambalpur ; Zayleymau, 

 Upper Burma (J)r. J. Anderson). 



Lea's description is amplified by the follow ing notes : — " Sliell 

 narrow elliptical, very transverse, very inequilateral, subangular 

 behind ; dorsal line nearly straight : substance of the shell very 

 thin ; beaks very slightly elevated and minutely waved at the tip ; 

 ligament long and slender ; epidermis smooth, dark brown ; rays 

 none ; cardinal teeth thin, bladed, single in the hft valve and 



