| 1a |
Only the right valve
decidedly convex (the left valve
is fairly flat); height
commonly exceeding 10 cm |
Patinopecten caurinus |
| 1b |
Both valves
decidedly convex; height less than 7 cm (except in the case of Hinnites
giganteus (now Crassodoma gigantea),
which reaches a height
of more than 10 cm; this species, after reaching a height of about 1
cm,
becomes permanently cemented to rock) |
2 |
| 2a |
Interior of both balves with purple blotch; free-living
until about
1 cm high,
then becoming cemented to rock by the right valve;
height
often exceeding 10 cm |
Crassodoma
gigantea
(in key as Hinnites giganteus) |
| 2b |
Interior of both
valves without a purple blotch near the hinge; not
permanently cemented
to rock (but it may be temporarily attached by a byssus);
height
not more than 6 cm |
3 |
| 3a |
With true external ribs (there may also be ruffles or
spines, but if
these are worn away, the ribs will still be evident); height
commonly greater than 3 cm |
4 |
| 3b |
Either without ribs or only with pseudoribs which
consist of raised
ruffles of the concentric ridges (if the ruffles, which may overlap one
another, are scraped away, no rib remains) |
6 |
| 4a |
Radial
ribs
of both valves
with
very prominent spines or ruffles, rough to the touch |
Chlamys
(Chlamys) hastata |
| 4b |
Valves
nearly
or quite smooth to the touch (if the ribs
have spines or knoblike excresences, these are so slight as to be
invisible
without magnification; the excresences, moreover, are generally
restricted
to the right valve) |
5 |
| 5a |
Both valves
with about 20-30 prominent ribs (ribs
of the right valve with ruffles but those of the left valve smooth;
common
shallow subtidal species) |
Chlamys
(Chlamys) rubida |
| 5b |
Both valves
with about 10 especially prominent ribs,
between which are less prominent ribs
(rare subtidal species in our region) |
Chlamys (Chlamys) behringiana |
| 6a |
With raised internal ribs (height
up to 2.5 cm) |
Family Propeamussidae:
Parvamussium alaskensis |
| 6b |
Without raised internal ribs |
7 |
| 7a |
Either without pseudoribs or with pseudoribs that are
about the same
caliber as the concentric ridges (height
up to 3 cm) |
Delectopecten randolphi |
| 7b |
With pseudoribs that are much more pronounced than the
concentric ridges |
Delectopecten vancouverensis |