| 1a |
Rostrum
about half the length of the rest of the carapace,
consisting largely of 2 slender, spinelike processes (these may be
fused
medially
for much of their length) |
2 |
| 1b |
Rostrum
not more than one-third or two-fifths the length of the rest of the carapace,
consisting of 2 broad, flattened processes (picture) |
3 |
| 2a |
Spinelike processes of rostrum
nearly parallel, at least in the proximal
half; dorsal surface of carapace
with a large, sharp tooth behind each eye (picture)
but otherwise rather smooth |
Oregonia
gracilis |
| 2b |
Spinelike processes of rostrum
diverging proximally
as well as distally;
dorsal surface of carapace
without a prominent tooth behind the orbit
of each eye, but otherwise rather spiny |
Chorilia
longipes |
| 3a |
Carapace,
including the rostrum,
about as wide as, or wider than, long |
4 |
| 3b |
Carapace,
including the rostrum,
decidedly longer than wide |
6 |
| 4a |
Carapace,
viewed from above, nearly hexagonal; lateral margins of carapace
extended into thin, winglike sheets, each with 2 sharp-tipped lobes;
dorsal
surface of carapace
nearly smooth; intertidal as well as subtidal |
Mimulus foliosus |
| 4b |
Carapace,
viewed from above, broadly oval to circular, lateral margins of carapace
not extended into winglike sheets with lobes; dorsal surface of carapace
with tubercles or spines, or both; strictly subtidal |
5 |
| 5a |
Rostrum
sharply inclined upward; dorsal surface of carapace
spiny; generally at depths greater than 1000 m |
Chionoecetes angulatus |
| 5b |
Rostrum
not sharply inclined upward; dorsal surface of carapace
roughened by tubercles but not especially spiny; at depths as shallow
as
20 m |
Chionoecetes
bairdi |
| 6a |
Carapace
with a prominent, sharp projection, directed outward or slightly
forward
on both sides of the body near or behind the middle |
7 |
| 6b |
Carapace
without a prominent, sharp projection on both sides of the body near or
behind the middle (such projections, if any, are limited to the
anterior
half of the body) |
9 |
| 7a |
Dorsal surface of carapace
almost smooth; distance between the eyes less than about 1/3 the
greatest
width of the carapace |
Pugettia
producta |
| 7b |
Dorsal surface of carapace
with tubercles; distance between the eyes about 1/2 the greatest width
of the carapace. |
8 |
| 8a |
Dorsal surface of merus
of cheliped
with some tubercles,
but not with a distinct ridge; posterolateral expansions of carapace
much broader basally than the next expansions anterior to them |
Pugettia richii |
| 8b |
Dorsal surface of merus
of cheliped
with an irregularly toothed ridge; posterolateral expansions of carapace
only slightly broader than the next expansions anterior to them |
Pugettia
gracilis |
| 9a |
Outline of body, as viewed from above,
lyre-shaped,
owing to a toothed
expansion of the carapace
on both sides of the anterior half; rostral
processes widest at the base (picture) |
10 |
| 9b |
Outline of body, as viewed from above, nearly
triangular, becoming
narrowed gradually toward the eyes; rostral
processes widest near the middle |
Scyra
acutifrons |
| 10a |
Length of carapace,
including rostrum,
about 1.5 times the width; at depths of 500 m or more |
Oregonia bifurca |
| 10b |
Length of carapace,
including rostrum,
about one and one-fifth times the width; in shallow water as well as at
considerable depths |
Hyas
lyratus |
