| 1a |
Edges of the siphonal
canal touching or nearly touching for at least part of the canal, so
this is essentially a closed tube |
2 |
| 1b |
Edges of the siphonal
canal not touching or nearly touching, so the canal is an open trough
for its entire length |
7 |
| 2a |
With a large tooth
on the outer lip of the aperture;
with 3 winglike axial excrescences, as well as unevenly spaced spiral
ridges; height up to about 8 cm (common intertidal and shallow subtidal
species)
 |
Ceratostoma foliatum
(Gmelin, 1791) |
| 2b |
|
|
| 3a |
|
|
| 3b |
|
|
| 4a |
|
|
| 4b |
|
|
| 5a |
|
|
| 5b |
|
|
| 6a |
|
|
| 6b |
|
|
| 7a |
Height decidedly more then twice the diameter |
Trophonopsis lasius |
| 7b |
Height not more then twice the diameter |
8 |
| 8a |
Axial
ribs stout, not at all like lamellae |
9 |
| 8b |
Axial
ribs rather thin lamellae,
sometimes frilly |
12 |
| 9a |
Height much less then twice the diameter; outer lip of aperture,
in mature or nearly mature specimens, thickened to the extent that it is
more than half the width of the aperture
(height up to about 3 cm; locally introduced with the Pacific oyster, Crassostrea
gigas) |
Ceratostoma inornatum |
| 9b |
Heght about twice the diameter; outer lip of aperture
not thickened to the extent that it is half the width of the aperture |
10 |
| 10a |
Interior of aperture
purplish or brownish; spiral ridges more obvious between the axial
ribs than where they intersect the ribs; on oysters and barnacles in
areas where the Atlantic oyster, Crassostrea virginica, has been
introduced |
Urosalpinx cinerea |
| 10b |
Interior of aperture
usually light, not purplish or brownish; spiral
ridges generally as prominent where they intersect the axial
ribs as between the ribs; on rocky shores |
11 |
| 11a |
Axial
ribs broad, nearly contiguous, rounded, not sharply elevated; height
up to about 2.5 cm (common inertidal species) (Ocenebra lurida in
original key) |
Paciocinebrina lurida |
| 11b |
|
|
| 12a |
|
|
| 12b |
|
|
| 13a |
|
|
| 13b |
|
|