141 



tooth also on the margin, at the base of which appears a second 

 and much smaller tooth ; posterior lateral gently curved, narrow, 

 sharp, falling between two equal sized lamellae in the left valve ; 

 anterior muscular scar moderately to slightly deep, posterior 

 muscular scar superficial. 



Long. 27, lat. 47'25 mm. 



Hob. Eivers of India ; Pegu (Ind. Mus. Coll.). 



The species seems to vary greatly in shape and colour, some 

 specimens, in the long series of the Indian Museum Collection, 

 being posteriorly much more rostrate than others, while in some 

 the dorsal margin is angled posteriorly and produced anteriorly. 

 In colour the species seems to vary from pale yellowish green to 

 dark blackish brown, and thus two extremes might easily be 

 taken at first sight for different species : there does not seem, 

 however, to be any clear line of demarcation between the many 

 varieties, all of which merge into one another when a sufficiently 

 large series is examined. 



273. Nodularia (Nodularia) pugio (Benson). 



Nodularia (Nodularia) pugio (Benson) ; Simpson, Washington, D.C., 



Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 814. 

 Unio pugio, Benson, A. M. N. II. x, 1862, p. 193 ; Sowerby, Concli. 

 Icon. pi. 45, fig. 516 j H. & T,, C. I. 1876, p. 5, pi. 10, fig. 7. 



Original description: Testa transverse elongato-triangulari, 

 linguaeformi, valde inequilateral!, compressiuscula, crassa, antiee 

 brevissima, subito descendente rotundata, postice sensim angus- 

 tiore, cuneiform!, clemum acuminata, margine dorsali recta, 

 ventral! convexiusculo, postice ascendente; umbonibus late 

 planatis, laevibus, prominentibus, carina umbonali subito obtuse 

 angulata, area interjacente versus cardinem descendente ; disco 

 subplanulato, laeviusculo, substriato ; dente cardinal! (valva> 

 dextrae)brevi, crassa prominente, radiato-sulcata, laterali elongata, 

 subduplicata, iutus crenulata : margarita albida, iridescente. 



Long. 21, lat. 42, diam. 16 mm. 



Hob. Neighbourhood of Ava, Pegu (Indian Mus. Coll.) ; also 

 recorded from the Barrack River, Silchar. 



A curious species whose smooth surface and anteriorly swollen 

 and posteriorly cuneiform shape easily distinguish it from any 

 other Indian members of the family. 



274. Nodularia (Nodularia) gratiosa (Philippi). 



Nodularia (Nodularia) gratiosa (Philippi) ; Simpson, Washington, 

 D.C., Smiths. Inst., Nat Mus. Proc. xxii, 1900, p. 815. 



Unio c/ratiosus, Philippi, Conch, i, 1845, p. 20, pi. l,fig. 5 ; Catlow 

 & Keeve, Conch. Norn. 1845, p. 59; ? Kiister, Conch. Cab., Unio, 

 1861, p. 239, pi. 80, fig. 3. 



Margaron (Unio) f/ratiosus, Lea, Syn. 1870, p. 32. 



