| 1a |
Shell with an oval or circular opening at the
apex
(photo)
or with a slit
just anterior to the apex
(photo) |
2 |
| 1b |
Shell without an oval or circular opening or slit (on
the interior
of the shell, however, there is a groove running from near the apex
to the anterior margin; this takes the place of the exhalant opening
typical
of the family; ribs very coarse, with nodules and other roughenings;
length
sometimes slightly greater than 7 cm; subtidal, mostly on vertical rock
cliffs) |
Arginula bella
(Gabb, 1865) |
| 2a |
Opening in shell oval or nearly circular, at the apex
(photo) |
3 |
| 2b |
Opening in shell a narrow slit, just anterior to the apex
(photo) |
4 |
| 3a |
Length of opening about one-third the length of the
shell (photo);
shell not more than 2 cm long, and covered by the mantle
when the animal is alive |
Fissurellidea
bimaculata
Dall, 1871 |
| 3b |
Length of opening about one-tenth the length of the
shell; shell often
5 cm long, only a small, marginal portion of it covered by the mantle
when the animal is alive |
Diodora
aspera
(Rathke, 1833) |
| 4a |
Anterior slope of shell with a slight seam extending
from the opening
to the margin |
5 |
| 4b |
Anterior slope of shell without a seam extending from
the opening to
the margin |
7 |
| 5a |
Primary
and
secondary
ribs of about the same size; margin nearly smooth, not
obviously dentate
where the ribs reach it (length up to about 2 cm) |
Puncturella decorata
Cowan and McLean, 1968 |
| 5b |
Primary
and secondary
ribs of distinctly different sizes; margin obviously dentate
where
the primary ribs reach it |
6 |
| 6a |
With about 30 primary
radial
ribs (count near the apex), these separated, as they approach
the margin,
by 1-3 secondary
ribs (when there are 3, the middle one may be nearly as
prominent as
the primary
ribs, especially at the margin); marginal serrations, where
the primary
ribs reach the margin, not projecting more than 1 mm (length
up to
3.5 cm) |
Puncturella multistriata
Dall, 1914 |
| 6b |
With 13-23 (usually about 16) sharp, raised primary
ribs, most of these separated, as they approach the margin,
by 3 or
4 faint secondary
ribs; marginal serrations, where the primary
ribs reach the margin, projecting 2-3 mm (length up to 4 cm) |
Cranopsis
cucullata
(Gould, 1846)
(Was Puncturella cucullata) |
| 7a |
Height generally equal to the width, and sometimes to
the length; with
about 27-33 radial
ribs; length up to about 1 cm |
Puncturella cooperi
Carpenter, 1864 |
| 7b |
Height not quite equal to the width; with about 49-63 radial
ribs; length up to 2 cm |
Puncturella
galeata
(Gould, 1846) |