tfODULABIA. 147 



Unio crispisulcatus, Lea, A. M. N. H. x, 1862, p. 193 ; Sowerby, 



Conch. Icon, xvi, 1866, pi. 49, fig. 262. 

 Margaron ( Unio) crispisulcatus, Lea, Syn. 1870, p. 149. 



Original description : Testa transverse subovata, subinsequi- 

 laterali ; antice rotundata, postice superne descendente, leviter 

 angulata, demum obtuse angulata, crassiuscula, compressiuscula ; 

 disco convexiusculo minutissime radiatim rugoso-costulato, costulis 

 nonnullis acute divaricatis, posterioribus latioribus ; umbonibus 

 prominentibus, contiguis, apicibus acutiuseulis ; epidermide luteo- 

 olivacea, postice fuscata, hie illic nonnunquam viridiscente ; 

 dentibus cardinalibus utriusque valvae duplicibus, lamellatis, late- 

 ralibus obliquis, modice elongatis, valvze sinistrae duplicibus : 

 margarita cseruleo-albida iridescente. 



Long. 28, lat. 45, diam. 36 mm. 



Hob. Bangong Eiver near Thyet-Myo, Burma (W. Theobald) ; 

 Pegu (Indian Mus. Coll.). 



To the above description is appended the following note : 



" The anterior cicatrices are distinct, the posterior confluent, 

 the apical ones above the moderate angular cavity, and running 

 under the cardinal tooth. 



*' The delicate sculpture over the whole disk of this shell is 

 peculiar. In form it does not approach any Gangetic type." 



A well-marked and apparently very constant form, the large 

 series of about twenty-three specimens in the Indian Museum 

 Collection, from the Irrawaddy near Thyetmio and Pegu, practi- 

 cally showing no variation whatever. 



283. Nodularia (Radiatula) lima, Simpson. 



Nodularia (Radiatula} lima, Simpson, Washington, D.C., Smiths. 



Inst,, Nat. Mus. Proc. xxii, 1900, p. 820. 

 Unio radula (Benson), Hanley, Rec. Biv. Shells, Supp. 1856, p. 382, 



pi. 23, fig. 41 ; H. & T., C. I. p. 5, pi. 10, fig. 3. 

 Dysonomia radtila, Eochebrune, Bull. Soc. Philom. Paris vi, 1882, 



p. 42. 



Original description : Transversely oboval, inequilateral, not 

 very thick, rather compressed, olivaceous, sculptured as in U. sco- 

 bina, but rather more linearly and transversely ; ventral and front 

 dorsal edges convex and subparallel; hinder extremity rounded, 

 narrower : umbonal ridge inconspicuous, umbonal slope simple ; 

 neither the eroded umbones nor the ligament prominent ; nacre 

 bluish ; umbonal cavity shallow ; hinder tooth strong, complicated ; 

 front lateral tooth elongated, a little curved. 



Long. 19, lat. 32 mm. 



Hah. Assam ; Siliguri and Sikkiin (Indian Mus. Coll.). 



Extremely variable in sculpture and form ; in some speci- 

 mens the corrugations extend over the whole surface of the shell, 

 while in others they are confined merely to the umbonal region ; 

 in general outline it varies from ovate to trapezoidal as the 



L2 



