| 1a |
Shell permanently cemented to a hard substratum
(usually rock), coiled
loosely or irregularly and generally twisted, resembling the calcareous
tube of a serpulid polychaete more then a snail shell (picture)
(picture) |
Family Vermetidae |
| 1b |
Shell not permanently cemented to a hard substratum,
either tightly
coiled or tubular, conical, or cap-shaped |
2 |
| 2a |
Shell tubular, conical, or cap-shaped, without obvious
coiling |
3 |
| 2b |
Shell obviously coiled, although the spire
may be short |
9 |
| 3a |
Shell tubular, slightly curved, the height more then
twice the diameter |
Family Caecidae |
| 3b |
Shell conical or cap-shaped, the height rarely
exceeding the greatest
diameter (photo) |
4 |
| 4a |
Shell with a dorsal opening at or near the apex
(photo)
(photo),
or with a slight indentation at the anterior margin (such an
indentation
is present only in the rare and subtidal Arginula bella;
it marks
the place where a groove on the interior of the shell, beginning at the
apex,
reaches the margin) |
Family
Fissurellidae |
| 4b |
Shell with neither a dorsal opening at or near the apex
nor an indentation on the anterior margin |
5 |
| 5a |
Interior of shell with a shelf (photo)
(photo) |
Family
Calyptraeidae |
| 5b |
Interior of shell without a shelf (photo) |
6 |
| 6a |
Apex
of the shell usually
at or anterior to the middle, sometimes slightly posterior to the
middle
(if only the shell is available, the open end of the horsehoe-shaped
muscle
scar faces anteriorly (photo),
except in the family Siphonariidae, in which the open end of a nearly
C-shaped
muscle scar faces the right side [left side, if the shell is observed
in
ventral view]) |
7 |
| 6b |
Apex
of the shell decidedly
posterior to the middle (at least as far as the beginning of the last
quarter)
(the foot secretes a calcareous base, and the animal remains attached
to
this) |
Family
Hipponicidae:
Hipponix
cranioides |
| 7a |
Outline of the shell, in dorsal view, not symmetrical,
the apex
slightly to the right of the midline; muscle scar (often indistinct)
nearly
C-shaped, its open end facing the right side (left side if the shell is
observed in ventral view); with a shallow siphonal groove passing
through
the open end of the muscle scar |
Subclass
Pulmonata,
Family Siphonariidae |
| 7b |
Outline of the shell, in dorsal view, symmetrical
(unless deformed
by an injury) (photo),
the apex
on the midline;
muscle scar horsehoe-shaped, its open end facing anteriorly (photo);
without a siphonal groove |
8 |
| 8a |
Interior of shell uniformly whitish, without any color
pattern; apex
in the anterior third of the shell; exterior with rather conspicuous
concentic
lamellae
(subtidal) |
Family Lepetidae |
| 8b |
Interior of shell usually with a color pattern of some
sort (a blotch
in the apical
region, marginal
markings, etc.) (photo);
apex
in the anterior or middle third of the shell (in the middle third in Acmaea
mitra, the only species in which the interior is uniformly
white);
concentric lines not often conspicuous |
Order
Patellogastropoda,
Families Acmaeidae,
Nacellidae,
and Lottiidae |
| 9a |
Abalones--shell low and earlike, with a low spire
near the posterior end, and with a series of holes (some closed) near
the
left side; length sometimes exceeding 10 cm (picture) |
Family
Haliotidae |
| 9b |
Shell generally not low and earlike (except in
Lamellariidae and Velutinidae),
and without a series of holes near the left side; only a few species
larger
then 10 cm, and nearly all of these have tall spires |
10 |
| 10a |
Shell (completely or almost completely internal in
Lamellariidae) with
a low profile, thus resembling the shell of a abalone (photo) |
11 |
| 10b |
Shell not resembling that of an abalone |
12 |
| 11a |
Shell thin, translucent white, and completely or almost
completely
internal |
Family Marseniidae |
| 11b |
Shell rather firmly calcified, covered by an almost
velvety periostracum,
and to a large extent external (photo) |
Family
Velutinidae |
| 12a |
Outer lip of the aperture
with a deep slit ( the shell, which has a short spire
above the proportionately large body
whorl, resembles that of a Margarites
or Lirularia
[Trochidae], its diameter being about equal to its height; found only
at
depths greater then 400 m) |
Family Scissurellidae |
| 12b |
Outer lip of the aperture
without a deep slit (there may, hovever, be a notch
or distinct siphonal
canal at the anterior end of the aperture,
and there may also be a slight notch on the outer lip near the
posterior
end of the aperture)
(includes most intertidal and subtidal prosobranch gastropods, and some
opisthobranchs and pulmonates) |
13 |
| 13a |
Length of the aperture
nearly equal to the height of the shell (if there is a spire,
it is not raised) |
14 |
| 13b |
Length of the aperture
not nearly equal to the height of the shell (there is a raised spire) |
15 |
| 14a |
Shell thick, similar in shape to that of a cowrie, with
a series of
teeth on the inside of the outer lip of the aperture;
aperture not decidedly wider in its anterior half than elsewhere;
height
about 3 mm |
Marginellidae:
Granulina margaritula |
| 14b |
Shell thin, not resembling that of a cowrie; without
teeth on the inside
of the outer lip of the aperture;
aperture usually widest in its anterior half; height up to nearly 2 cm,
but much smaller in some species |
Subclass Opisthobranchia,
Order Cephalaspidea |
| 15a |
Much of the periostracum
in the form of conspicuous hairs or bristles |
16 |
| 15b |
Periostracum
not in the form of conspicuous hairs or bristles |
17 |
| 16a |
With a prominent siphonal
canal that is about 1/3 the total length of the aperture
(photo);
height up to about 12 cm (or more) |
Cymatiidae:
Fusitron
oregonensis |
| 16b |
Without a distinct siphonal
canal, but the anterior of the aperture
is angled in such a way that it forms a small spout; height generally
less
than 4 cm |
Capulidae
(formerly Trichotropidae) |
| 17a |
Anterior end of the aperture
without a distinct siphonal
notch, spout, or canal
(photo) |
18 |
| 17b |
Anterior end of the aperture
with a distinct siphonal
notch, spout, or canal |
34 |
| 18a |
Interior of shell pearly (except in Halistylus
pupoideus, family
Trochidae); with an operculum
(photo) |
19 |
| 18b |
Interior of shell not pearly (it may, however, be
colored); with or
without an operculum |
20 |
| 19a |
Operculum
thin
and horny, with numerous spiral lines (photo) |
Family
Trochidae |
| 19b |
Operculum
calcified
and rather thick, with only a few spiral lines |
Family Turbinidae |
| 20a |
Diameter of the shell much greater than the height (aperture
almost circular, equal to about half the total diameter, which does not
exceed 4 mm; without periostracum) |
Vitrinellidae:
Vitrinella
columbiana |
| 20b |
Height of the shell equal to or greater than the
diameter |
21 |
| 21a |
Columella
with
1 or more distinct folds or ridges; height less than 1 cm |
22 |
| 21b |
Columella
without
any folds or ridges; height may exceed 1 cm |
24 |
| 22a |
|
|
| 22b |
|
|
| 23a |
|
|
| 23b |
|
|
| 24a |
Diameter about equal to the height; shell generally
almost globose,
consisting mostly of the body
whorl (umbilicus
either conspicuously open or covered by an obvious callus;
height of some species attaining 10 cm) |
Family
Naticidae |
| 24b |
Height decidedly greater than the diameter; shell not
almost globose,
the spire
usually at least
one-sixth of the total height |
25 |
| 25a |
Height not more than twice the diameter |
26 |
| 25b |
Height considerably more than twice the diameter |
30 |
| 26a |
Umbilicus
a slit
between the columella
and the body
whorl
(generally on eelgrass or on algae, especially kelps, mid- to low
intertidal
and subtidal) (formerly Family Lacunidae) |
Subfamily
Lacuninae of
Family Littorinidae |
| 26b |
Umbilicus
absent
or indistinct (in some species, there is a narrow space between the body
whorl and the edge of the inner lip of the aperture) |
27 |
| 27a |
Height commonly exceeding 5 mm, and in some species
slightly exceeding
1.5 cm; operculum
horny; periostracum
not uniformly tan or brown (Almagorda subrotundata
is brown, but
usually has spiral banding) (mostly at higher tide levels on rocly
shores,
or on rocks, concrete and wood in bays, sometimes in salt marshes) |
Family
Littorinidae |
| 27b |
Height not exceeding 4 mm; operculum
horny or calcareous; periostracum
sometimes uniformly tan or brown (Assiminea californica,
Assimineidae,
inhabits salt marshes, but members of the other families to which this
couplet leads are typically found at lower levels of rocky or gravelly
intertidal areas) |
28 |
| 28a |
|
|
| 28b |
|
|
| 29a |
|
|
| 29b |
|
|
| 30a |
Shell highly polished, in some species slightly bent; suturesbetween
whorls
so slightly indented that they are barely evident (whorls
themselves, moreover, are nearly flat); parasitic on echinoderms, and
strictly
subtidal |
Family Eulimidae |
| 30b |
Shell not usually highly polished, and not bent; sutures
between whorls
distinct;
not parasitic on echinoderms (but the Epitoniidae are parasitic on
various
cnidarians) |
31 |
| 31a |
Spire
decidedly tapered
and generally with more than three whorls;
not typically found at higher tide levels in salt marshes |
32 |
| 31b |
Spire
scarcely tapered,
and generally with only 3 whorls
(the older whorls
disappear
and the uppermost surviving whorl
is usually very short and smoothly rounded; typically at highter tide
levels
in salt marshes |
Truncatellidae:
Cecina
manchurica |
| 32a |
Height of the spire
shorter than the body
whorl; spire usually with 4 or 5 surviving whorls;
shell sculpture limited to prominent axial
ribs, and when the shell is viewed with the aperture
lowermost and facing the observer, the ribs are more nearly parallel to
the left side of the shell than to the right side |
Rissoinidae:
Rissoina
newcombiana |
| 32b |
Height of the spire
considerably greater than the height of the body
whorl; spire
usually
with at least 6 surviving whorls;
shell sculpture sometimes limited to axial
ribs, but if so, the ribs are more or less parallel to both
sides of
the shell |
33 |
| 33a |
With both axial ribs
and spiral
ridges
(the intersections of these sometimes form beads), or with spiral
ridges only |
Family Turritellidae |
| 33b |
Sculpture limited to axial
ribs (except for a single spiral
ridge near the base of the body
whorl) |
Family
Epitoniidae |
| 34a |
Upper portion of the outer lip of the
aperture with an anal
notch
If the lip has been fractured, the contours of the growth lines nearest
the lip are likely to indicate that an indentation had been
present.
In species that do not have a distinct anal
notch, the following combination of characters may enable one
to recognize
them as members of this family; width of the aperture
less than one half, and usually less than one third, the height of the
aperture;
prominent
axial
ribs;
foot milky white. Presence of an anal
notch, however, is the most reliable feature.
In certain species of Antiplanes, the shell is
coiled sinestrally
rather than dextrally,
and this is helpful in assigning them to the Turridae. Most
members
of the family are subtidal and they typically inhabit soft
sediments.
None in our region is likely to be found in a rocky intertidal habitat. |
53 Turridae |
| 34b |
Upper portion on the outer lip of the aperture
without an anal
notch
or trace of a notch |
35 |
| 35a |
Shell highly polished, without any sculpture other then
fine growth
lines; widest part of the aperture
(near its lower end) less then half the diameter of the shell (picture);
operculum
inconspicuous; typically in sandy substrata |
Family
Olividae |
| 35b |
Shell not polished, and usually with at least some
sculpture; widest
part of the aperture
(generally near its middle) usually at least half the diameter of the
shell;
operculum
usually conspicuous and large enough to close the aperture
tightly (picture
picture);
not necessarily limited to sandy substrata |
36 |
| 36a |
Lowermost portion of the body
whorls including the siphonal
canal, set off from the rest of it by a conspicuous groove
that [may
even] interrupt the axial
ribs (photo)
[though in Nassarius fossatus the axial ribs do not
extend this
far anteriorly on the body whorl]. |
Family
Nassariidae |
| 36b |
Lowermost portion of the body
whorl not set off from the rest of it by a conspicuous groove
that
interrups the axial
ribs |
37 |
| 37a |
Shell with at least 8 distinct whorls,
not counting 1 or 2 that may have been worn away at the apex
(in specimens that have been abruptly worn down to 4 or 5 whorls,
one can estimate, on the basis of the surviving portion of the shell,
that
about 10 whorls have developed; height not exceeding 4 cm |
38 |
| 37b |
Shell with not more than 7 whorls,
even if none appears to have been worn away, except in specimens whose
hight commonly exceeds 12 cm |
41 |
| 38a |
Siphonal canal half the total height of the aperture;
axial ribs prominent,
not forming beads where they intersect the faint spiral ridges |
Family
Neptuneidae:
Exiliodea rectirostris |
| 38b |
Siphonal canal less than half the total height of the
aperture (photo);
axial ribs and spiral ridges sometimes forming beads where they
intersect |
39 |
| 39a |
Siphonal canal short but obvious; spiral ridges
distinctly (and sometimes
conspicuously) beaded where intersected by the axial ribs (photo) |
40 |
| 39b |
Siphonal canal barely evident; spiral ridges beaded in
some species
that have axial ribs, but not in the most common species (Bittium
eschrichtii); which lacks axial ribs |
Family
Cerithiidae |
| 40a |
Siphonal canal narrow, directed toward the left at a
nearly right angle
to the long axis of the shell (as the shell is viewed with aperture
lowermost
and facing the observer) (photo);
with about 12 axial ribs; height up to 3.5 cm; usually in salt marshes |
Family Batillariidae:
Batillaria
attramentaria |
| 40b |
Siphonal canal broad, directed to the left at about a
45 degree angle
from the long axis of the shell; with at least 12 axial ribs (and
sometimes
more than 30); height not often exceeding 1 cm |
Cerithiopsidae |
| 41a |
Shell either with axial
ribs as well as spiral
ridges, or with only spiral
ridges |
42 |
| 41b |
Shell with only axial
ribs |
Family Volutidae |
| 42a |
Shell sculpture limited to spiral
ridges |
55 |
| 42b |
Shell with axial ribs
(these may be low and incospicuous, however) or thin axial lamellae
(picture),
as well as with spiral
ridges |
43 |
| 43a |
Axial
ribs limited
to the spire
(the body
whorl may have a few irregularly spaced grooves that are
perpendicular
to the spiral
ridges,
and young specimans of Searlesia dira, under 2 cm
long, have axial
ribs on the body
whorl) (photo) |
44 |
| 43b |
Axial
ribs or
lamellae
extending to the body
whorl, even though they may be less distinct on the body
whorl than on the spire |
45 |
| 44a |
Columella
with
2-5 folds; periostracum
light brown; spiral
ridges faintly evident on the inside of the outer lip of the aperture;
subtidal |
Family Cancellariidae:
Neoadmete modesta |
| 44b |
Columella
without
folds; periostracum
gray; dark lines in the furrows between spiral
ridges of the body
whorl visible on the inside of the aperture;
intertidal and subtidal |
Family Buccinidae:
Searlesia
dira |
| 45a |
Axial
ribs on
the body
whorl restricted
to the upper half of it (if continued into the lower half of the body
whorl, they become much less prominent) (photo) |
46 |
| 45b |
Axial
ribs distinct
on at least much of the lower half of the body
whorl, and as prominent as those on the upper half of the body
whorl |
49 |
| 46a |
With a series of folds on the inside of the outer lip
of the aperture
as well as on the columella |
Family Columbellidae
(in part) |
| 46b |
Folds sometimes present either on the inside of the
outer lip of the
aperture
or on the
columella,
but not on both |
47 |
| 47a |
With folds on the inside of the outer lip of the aperture
(these coincide with spiral
ridges on the outside of the body
whorl); without folds on the columella |
Family Fusinidae |
| 47b |
Without folds on the inside of the outer lip of the aperture;
with or without folds on the columella |
48 |
| 48a |
Axial
ribs rather
sharp; with 2-5 (usually 2 or 3) folds on the columella |
Family Cancellariidae:
Admete gracilior |
| 48b |
Axial
ribs low
and broad; without folds on the columella |
Family
Neptuneidae:
Plicifusus griseus
(now Family
Buccinidae,
Colus
griseus) |
| 49a |
Siphonal
canal
(measured from the angle in the outer lip of the aperture
where the canal begins) one-third to one-half the total height of the aperture |
50 |
| 49b |
Siponal
canal
decidedly less than one-third the total height of the aperture
(picture) |
51 |
| 50a |
Either with axial
ribs and spiral
ridges equally well developed and prominent, or axial ribs
represented
by thin lamellae
and
spiral
ridges faint |
Family
Muricidae |
| 50b |
Axial
ribs poorly
developed in comparison with the prominent spiral ridges |
Family Neptuneidae |
| 51a |
Axial sculpture consisting of thin, frillylamellae
(photo);
spiral
sculpture, which may be obscured by the lamellae,
consisting of 1 or 2 prominent ridges
on each whorl
(picture) |
Nucellidae:
Nucella
lamellosa |
| 51b |
Axial sculpture consisting either of fairly broad ribs
or of wrinkles (these may be irregular and discontinuous), but not of
frilly
lamellae;
spiral sculpture consisting of closely spaced spiral
ridges |
52 |
| 52a |
With 2 or 3 folds on the columella |
Cancellariidae:
Cancellaria
crawfordiana |
| 52b |
Either with 1 fold or none on the columella |
53 |
| 53a |
Without a fold on the columella;
periostracum,
if persistent, straw-colored or dark brown |
Family Neptuneidae
(in part) |
| 53b |
With 1 fold on the columella;
periostracum
blackish or whitish |
54 |
| 54a |
Periostracum
blackish, thick, cracked, but otherwise more or less continuous except
where the spire
is eroded;
inside of aperture
purplish brown; axial
ribs and spiral
ridges about the same size; height up to about 2.5 cm;
intertidal,
in mudflats |
Nassariidae:
Ilyanassa
obsoleta |
| 54b |
Periostracum
whitish or dull brown; inside of aperture
white or pinkish; axial
ribs much more pronounced than the spiral
ridges; height up to 7 cm; subtidal |
Family
Buccinidae:
Buccinum spp |
| 55a |
Columella
with
2 or more folds |
56 |
| 55b |
Columella
without
folds |
57 |
| 56a |
Spiral
ridges
present over the entire shell; columella
with about 5 folds; restricted to deep water |
Family Volutomitridae |
| 56b |
Spiral
ridges
present only on the lowest part of the body
whorl, near the siphonal
canal; columella
with 2 or 3 folds; intertidal to shallow subtidal |
Family
Columbellidae
(in part) |
| 57a |
Sculpture consisting of closely spaced spiral
ridges (in Alia, Columbellidae, these are
faint and restricted
to the lower half of the body
whorl, and are sometimes absent) |
58 |
| 57b |
Sculpture consisting of only 1 or 2 prominent ridges on
each whorl
(the lower part of the body
whorl generally has a number of smaller ridges; in occasional
specimens
of Nucella emarginata, Nucellidae, which typically
has spiral
ridges over most of the shell, the ridges may be obscure) |
Family Nacellidae
(in part) |
| 58a |
Spiral
ridges
faint and limited to the lower half of the body
whorl (they are most likely to be visible near the columella;
use magnification); height up to about 1 cm |
Family
Columbellidae
(in part) |
| 58b |
Spiral
ridges
(these may be faint) distributed over all of the larger whorls;
height generally greater than 1 cm |
59 |
| 59a |
With a sharp tooth on the lower half of the outer lip
of the aperture
(picture) |
Nucellidae:
Acanthina
spirata |
| 59b |
Without a sharp tooth on the lower half of the outer
lip of the aperture |
60 |
| 60a |
Siphonal
canal
less than one-fourth the total height of the aperture;
height generally less than 4 cm; common intertidal species |
Nucellidae
(in part) |
| 60b |
Siphonal
canal
one-fourth to one-third the total height of the aperture
(the outer lip of the aperture usually has an angular indentation where
the canal begins); height commonly more than 4 cm in most species;
strictly
subtidal |
Family
Neptuneidae
(in part) |
