302 Records of the Indian Museum. [VoL ar 
ted; dorsal margin sloping towards the posterior side; ventral 
margin nearly straight; anterior side obliquely and rapidly slop- 
ing above, somewhat rounded below; posterior side produced, 
very obtusely rounded, angled below; hinge normal. 
The dimensions of the type specimen are as follows :— 
Long. 13°25, lat. 23, diam. 75 mm. 
Those of a larger, though imperfect individual are— 
Long. 17, tat. 315, diam. 11°5 mm: 
Hab.—Manikpatna, oyster-beds. 
Since the above was written the author has seen more speci- 
mens of this species from the Chilka Lake, the largest of which 
yields the following measurements :— 
Long. 27°5, lat. 47, diam. 17°25 mm. 
Family UNGULINIDAE. 
Diplodonta satparaensis, sp. n. 
(Figs. 14, 14a-b, p. 301.) 
Shell ovately rhomboidal, fragile, slightly glossy, whitish, 
covered with a very thin, pale greenish yellow periostracum, 
irregularly finely and closely concentrically striate; umbones 
small, but slightly prominent; dorsal margin arched; ventral 
margin anteriorly sloping, posteriorly rounded; anterior side 
angled above, then descending in a rather oblique curve; poste- 
rior side sloping, rather abruptly rounded; right valve bearing 
two small cardinal teeth, of which the anterior is short and slop- 
ing and the posterior narrowly bifid above, broadly so. below ; 
left valve also bearing two cardinals of which the anterior is 
rather narrowly bifid and the posterior very fine and oblique. 
Long. 19, lat. 20°5 mm. 
Hab.—Channel between Satpara and Barhampur, 8-20 ft. 
(Type); swamp inside bar N. of Barhampur Id.; channel off 
Satpara, 16-20 ft.; Kalidai Id.; between Mahosa and Satpara, 
6 ft.; Satpara Bay; channel off Barhampur Id., 10-20 ft.; chan- 
nel off Barhampur Id., 6-9 ft.; channel between Barnikuda and 
Satpara, 6} ft.; southwards from Mahosa, 5-9 ft.; Mahosa, Bar- 
hampur Id. 
Diplodonta barhampurensis, sp. n. 
(Figs. 15, 15a, p. 301.) 
Shell inflated, subequilateral, roundly trigonal, covered with 
a dark brown periostracum, finely concentrically striate; um- 
bones rather large, prominent; dorsal margin somewhat angularly 
arched; ventral margin rounded; anterior side rounded; poste- 
rior side obtusely rounded; hinge normal. 
Long. 13°75, lat. 14°75, diam. Io mm. 
Hab.—Channel off Barhampur Id., 10-20 ft. 
