ckagin.] DESCRIPTIONS OF SPECIES. 75 
height; anterior, ventral, and posterior sides rounded; dorsal side 
abruptly and emarginately excavated before the beaks to a point dis- 
tant one-fourth of the shell length, where it joins the anterior side in 
an obtuse angle, the posterior part of the dorsal side declining in a 
nearly straight line, with some convexity near the beaks, to a point 
two and a half times as remote, where it makes an obtuse angle with 
the posterior border; beaks low, with apex curved forward: lunule 
large, about twice as long as wide, abruptly and rather deeply im- 
pressed; margins entire; surface ornamented with rather coarse, 
rounded, subdued, concentric costellse separated by equal or narrower 
intervals, each costella making an irregular and gentle undulatory 
flexure as it approaches the posterior part of the dorsal margin. 
Measurements. — In an accidentally somewhat compressed specimen, 
height, 21 mm.; length, 22 mm.; breadth, 7 mm. In a second exam- 
ple, height, 20 mm.; length, 19 mm.; breadth, 10 mm. In a third, 
height, 32 mm.; length, 30.5 mm.; breadth about 10 mm. 
Occurrence. — Three examples were obtained from the locality 1| 
miles east of Malone station. 
In the absence of a satisfactory knowledge of the hinge details, 
the species is here placed in the genus Lucina because of the abruptly 
excavated and rather deep lunule, the lunule in Cyprimeria being 
feebly excavated or lacking. 
Lucina planiuscula sp. n. 
Pi. XIII, fig. 3. 
Shell of intermediate size for Lucina, thick-valved, broadly sub- 
oval, rather inflated, the breadth equal to more than half of the 
height, height equaling about five-sixths of the length, moderately 
inequilateral, the posterior side being between three-fourths and four- 
fifths as long as the anterior, the latter but little contracted; beaks 
little prominent; surface nearly plain, ornamented with inconspicu- 
ous, concentric raised lines and striae, which on the major part of the 
surface are more or less obsolete, but are more distinct on the anterior 
and posterior marginal regions, the raised lines on the latter being 
very fine and intervaled on the upper part, becoming coarser and 
more crowded below. 
Measurements. — Height, 2G.5 mm.; length, 31 mm.; breadth, 15 
mm. ; in another example, height, 28 mm. ; length, 31 mm. 
Occurrence. — Four shells and about a dozen casts of this fossil 
were collected in foothills in the northwest end of Malone Mountain, 
about 2 miles east-southeast of Finlay station. 
From Lucina coetoi C. and A., the L. planiuscula appears to differ 
chiefly by its more strongly inflated and much less strongly inequi- 
lateral shell and its plainer ornamentation. 
