152 AMERICAN MARINE CONCHOLOGY. 
somewhat pointed behind; white or pink, covered with a dusky 
epidermis. Teeth, two in each valve, slender and slightly diverg- 
ing, the largest grooved.. 
Length 25, height 20 mill. 
Whole Coast, Arctic Seas, N. Europe. 
2. M. caLcAREA, Chemnitz. Fig. 368. 
(Tellina.) Conch. Cab., vi. 140, f. 186. 1782. 
Tellina sabulosa, Spengler, Skrivt., Nat. iv., Pt. 2. 1798. 
Tellina proxima, Gray, Zool. Beechey’s Voy., 154, t. 44, f. 4. 1839. 
Tellina sordida, Couthouy, Bost. Journ. Nat. Hist., ii. 59, t. 3, f. 11. 
Shell thin and fragile, inequilateral, subtriangular, slightly 
gaping. Epidermis thin and brittle; beneath which the surface 
is marked with numerous incremental lines. Beaks very small 
and behind them the margin slopes away in nearly a straight 
line. Teeth two in each valve, the largest bifid. White, covered 
by a thin, brownish epidermis. 
Length 22, height 15 mill. 
Arctic Seas to New York. 
Wider and more triangular and depressed than the preceding 
species. 
3. M. susrosgA, Conrad. Fig. 369. 
Am. Journ. Conch., vi. 71, t. 1, f. 3. 1871. 
Subtriangular, equilateral, convex ; substance very thin; beaks 
slightly prominent, direct; posterior side cuneiform; ventral 
margin rounded, disk minutely striated concentrically, white or 
rosaceous and glossy, with a thin, pale ochreous epidermis ; cardi- 
nal tooth in the left valve compressed, with a minute linear sulcus. 
Raritan Bay, N. J. ; Delaware Bay. 
Doubtful Species. 
4. M. renvis, Da Costa. Fig. 370. 
(Tellina.) Conrad, in Say’s American Conchology, vii. t. 64, f. 3. 
Shell oval-triangular, irregularly striate concentrically ; each 
valve with two teeth and one of them with lateral teeth. 
Sullivan’s Island, 8. Car. 
The above meagre description and figure represent a shell sent 
to Mr. Say by Prof. Ravenel of Charleston, 8. C., which Mr. Con- 
rad has identified as MZ. tenuis. I am not aware that it has since 
been found on our coast. 
