724 APPENDIX L 
from beak to base; cavity most capacious between the umbones.—Plate 17, fig. 9, 
natural size. 
Astoria, Oregon. 
[Length about 13 inches; height 3 inch; beak 3 inch back of the front; apical angle 
140°.] 
Venus Bisecta (Conrad).—Oblique, subrhomboidal, ventricose, with robust lines of 
growth. Anterior side very short, truncate, angulate below, having a submarginal -ver- 
tical furrow, and the inferior margin at its termination slightly excavate. Posterior sur- 
face strongly excavate from the upper side of the beak to the posterior margin, and sub- 
carinate below the excavation ; ligament and supero-posterior margin forming together a 
regular curve. Basal margin arcuate, a little tumid behind the middle.—Plate 17, figures 
10, 10 a, natural size. 
Astoria, Oregon. 
[Length 2 inches; height {835 L.; thickness 34 L. or 565 H.; distance anterior to 
beak ¢ inch; apical angle 120°. Valves quite thin.] 
Venus ancustirrons (Conrad).—Obliquely cordate, ventricose. Anterior side nar- 
row, rounded. Posterior extremity somewhat truncated, arcuate ; ligament margin ele- 
vated, arcuate; basal margins arcuate. Exterior surface everywhere convex, marked 
with fine lines of growth.—Plate 17, fig. 11, natural size. 
Astoria, Oregon. 
[Length 17 inches; height 770, L., or 14 inches ; part anterior to beak 5 lines ; apical 
angle 134° ; valves quite thin.] 
VENUS LAMELLIFERA (Conrad.)—Subtrigonal, ventricose, ligament margin very ob- 
lique and slightly curved, long, posterior margin direct, truncate ; basal arcuate. Lateral 
surface everywhere convex, and having thin concentric elevated lamellz.—Plate 17, fig. 
12, 12 a, natural size. 
Astoria, Oregon. 
[Length 2 inches ; height ,°3, L.; valve very stout; cast excavate just below palleal 
impression. | 
VENUS BREVILINEATA (Conrad).—Subtrigonal, ventricose. Anterior extremity trun- 
cate ; ligament margin elevated, curved; posterior margin subtruncate; basal margin 
strongly arcuate, The specimen is a cast, and it is remarkable for a series of irregular 
vertical impressed lines or sulci, towards the base, which must correspond with promi- 
nent lines on the interior of the valve.-—Plate 17, fig. 13. 
[Length of cast 2 inches; height ;°°, L.; thickness 33, L. The irregular sulci on the 
lower half of the cast are nearly half an inch long, and extend upward from the palleal 
impression. The sinus in the palleal impression is acute triangular. The surface of the 
cast is faintly concentric undulate. | 
[Norr.—Figures 1, 1 a, plate 18, represent still another Venus, with a very thick 
valve, and smooth cast, having the sides evenly convex. It resembles the angustifrons, 
but is hardly as ventricose, and the valve in that is very thin. Length of cast 23 
inches ; height 1:6 inches ; thickness 1 inch.] 
