WHITE. JURASSIC FOSSILS. 149 
Genus ASTARTE Sowerby. 
ASTARTE PACKARDI (sp. nov.). 
Plate 37, fig, 6 a and b. 
Shell subcireular in marginal outline, moderately and almost regularly 
convex; its length and full height almost equal, or the latter a trifle less 
than the former; margin forming a continuous subelliptic curve all the 
way around from the posterior end of the hinge to the lower end of the 
lunule; hinge margin short and gently convex; beaks placed sub- 
centrally, rather small but prominent, and turned forward; lunule mod- 
erately large, rather deeply impressed and clearly defined, its abruptly- 
inflected borders giving a concave appearance to that portion of the 
shell as seen by lateral view. Surface marked by somewhat numerous 
and regular concentric undulations and, between these, by minute striz 
of growth. Hinge unknown. 
Transverse length, 20 millimeters; height from base to beaks nearly 
one millimeter less. 
This shell is probably not a true Astarte as that genus is recognized. 
among living forms, but it probably belongs to a section to which Gabb 
gave the name Hriphyla. As the hinge 1s unknown, however, I prefer 
to assign it to Astarte, since its visible characters indicate it to be closely 
related to, ifnotidentical with, that genus. Itresembles the A. ventricosa 
of Meek from the Jurassic rocks of California, as described and figured 
in the Paleontology of California, vol. 1, p. 50, pl. 8, fig. 5, but it is more 
nearly circular in marginal outline than that shell, less narrowly rounded 
in front, and the beaks are smaller and more pointed. 
Position and locality.—Jurassic strata, near Como Station, on the Union 
Pacific Railroad, Wyoming, where it was discovered by Prof. A. S. 
Packard, jr., in whose honor the specific name is given. He found it 
associated with Humicrotis curta, Belemnites densus, and other well-known 
Jurassic forms. 
Genus CARDINIA Agassiz. 
CARDINIA PRZECISA (Sp. NOV.). 
Plate 37, figs. 7a and b. 
Shell subovate in marginal outline, moderately and somewhat regu- 
larly convex; beaks small, approximate, situated near the front, and 
turned slightly inward and forward; front slightly concave below the 
beaks, giving an obliquely truncated appearance to the upper anterior 
portion; dorsum gently convex longitudinally from beaks to the pos- 
tero-dorsal portion, but concave laterally so as to nearly or quite ob- 
seure the ligament from side view; ligament external, well developed, 
but small and rather short. From front to rear, below a horizontal line 
drawn throvgh the mid height of the shell, its border forms an almost 
true semi-ellipse; posterior border somewhat regularly rounded. Sur- 
face marked by concentric lines and undulations of growth. 
Length, 38 millimeters; height, 28 millimeters; thickness, both valves 
together, 18 millimeters. 
This shell seems to be a true Cardinia, but it is the first species of 
that genus that has, to my knowledge, been found in American Jurassi¢ 
