130 
than the height; umbones moderately produced, iunule nearly 
obsolete; hinge margin straight, oblique, lengthened, the 
surface of the valves ornamented with a few ruge round the 
umbones, which pass downwards into closely arranged irregular 
strie. Height 7 lines, diameter 8 lines. 
Position and locality,—the Clypeus Grit, Rodborough Hill. 
AsTaRTE suB-ancuLATA. PI. IV, figs. 9, 9a. 
Shell small, convex, subtrigonal, tumid, inequilateral, umbones — 
produced, large, incurved ; anterior to the middle of the valves 
hinge border curved, lower border nearly straight, but sharply 
curved at the anterior and posterior extremites, lunule large 
ovate; the surface with concentric obtuse ribs (about 20) 
separated by somewhat narrower interstitial spaces. 
The small subtrigonal tumid form of this shell separates 
and distinguishes it from contemporary species. Height and 
diameter, 6 lines. 
Geological position and locality,—the Clypeus Grit of 
Rodborough Hill. Very common. 
ASTARTE DEPRESSA, GotpF. Var. Rodborensis. 
Pl. IV, figs. 10, 10a. 
Shell suborbicular, rather depressed, umbones moderately 
prominent, nearly mesial, slightly incurved, lunule nearly obso- 
lete; hinge border nearly straight, oblique, posterior border 
slightly produced; the surface has a few small closely arranged 
ruge near the apex; the remainder of the surface is concen- 
trically striated with several faintly marked plications of growth. 
Allied to A. striato costata Munst., but is distinguishable from 
that species by its rounded and more depressed form, less 
incurved umbones, and smaller lunule. Height and lateral 
diameter, 10 lines. 
Quenstept has figured three examples of Astarte depressa 
(Der Jura Pl. LXVII, figs. 29, 80, and 33), each of which has 
a more elliptical form, and fig. 29 is more depressed than our 
shell. These shells, with A. Striata costata, and A. clypeata, 
fig. 7, form a group, having similar surface markings, but 
. 
: 
mah 
