190 



315. Laxnellidens nongyangensis, Preston. 



Lamellidens nonyyanensis, Preston, Rec. Ind. Mus., Calcutta, vii, 

 1912, p. 306. 



Original description : Shell very elongately ovate, inflated, 

 covered with a blackish-brown, finely laminiferous periostracum, 

 concentrically marked with rather coarse lines of growth ; dorsal 

 margin anteriorly somewhat straight, posteriorly arched above, 

 sloping and slightly excavated below; ventral margin scarcely 

 rounded ; anterior side abruptly descending ; posterior side 

 rostrate, obtusely rounded ; cardinal teeth very anteriorly situate, 

 triangular, erect ; lateral teeth elongate, also erect, terminating 

 posteriorly in an abrupt slope ; anterior scars deeply marked, 

 posterior scars lightly impressed ; interior of shell flesh-coloured, 

 shading to bluish ; iridescent, minutely pitted and granulate. 



Long. 45, lat. 94 mm. 



Hal. Nongyang Lake, South of Patkai. 



The type is in the Indian Museum. 



3L6. Lamellidens phenchooganjensis, Preston. 



Lamellidens phcnchooganjensis, Preston, Rec. Ind. Mus., Calcutta, 

 vii, 1912, p. 306. 



Original description : Shell very elongately ovate, posteriorly 

 obtusely rostrate, dark blackish-brown, sculptured with fine con- 

 centric striae, crossed, especially in the anterior median region, by 

 fine, slightly distant, transverse, radiate striae, thus presenting a 

 minutely wrinkled appearance ; umbones flattened, much eroded ; 

 dorsal margin anteriorly gently sloping, posteriorly more rapidly 

 sloping in a slight curve ; ventral margin scarcely rounded ; 

 anterior side angled above, gently rounded below ; posterior side 

 produced, angularly rounded; hinge-teeth very elongate, some- 

 what fine ; anterior scars ovate, moderately impressed ; posterior 

 scars roughly triangular, not well impressed: interior of shell 

 shading from pale brown to bluish, nacreous, marked, especially 

 towards the anterior ventral region, with very shallow radiate 

 furrows. 



Long. 42, lat. 86 mm. 



Nab. Phenchooganj, Central Sylhet. 



The type specimen is in the Indian Museum. 



317. Lamellidens mainwaringi (Nevill, MS.},* (Preston.) 



Lamellidens mainwaringi (Nevill, MS.), Preston, Rec. Ind. Mus. 

 Calcutta, vii, 1912, p. 306. 



Original description : Shell rather small, cuneate, covered with 

 a finely laminiferous periostracum ; both valves marked with 

 rather fine, concentric, and finer transverse, radiate, scratch-like 



