Gastropods

Rissoidae

Oak Bay, WA Oak Bay, WA, intertidal

Alvania compacta (Carpenter, 1864)
Compact Alvania
intertidal to 182m northern Mexico to Alaska size to 3mm
This is infrequently found due to its tiny size. The shell is somewhat variable in size proportions and sculpture. Usually the early whorls exhibit a crosshatch type sculpture. This may become less prominent in the later whorls. The protoconch is smooth. The shell is brown in color.
(synonyms - Alvania filosa, Alvania pedroana)

Caecidae

Ucluelet, BC
Caecum crebricinctum Carpenter, 1866
Giant Caecum
intertidal to subtidal size to 6mm
northern Mexico to Alaska
This species is rarely found due to its small size.
It grows in a tube shape with a plug on one end.
As it grows, previously plugged portions fall off.
This shell has numerous fine axial rings.

Barleeiidae

Clayoquot Sound, BC Haida Gwaii, BC Monterey, CA

Pseudodiala acuta (Carpenter, 1864)
Acute Barleysnail
intertidal to 73m northern Mexico to southern Alaska size to 5mm
This species has a smooth, brown shell which is shiny. It may also exhibit a dark brown axial pattern. It is large for a Barleeia.
(synonyms - Barleeia acuta, Diala acuta, Barleeia marmorea, Barleeia dalli)

Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.

Ucluelet, BC
Onoba carpenteri (Weinkauff, 1885)
intertidal to subtidal size to 2.6mm
northern Mexico to Southeast AK
This is infrequently found due to its tiny size. It exhibits a fine crosshatch sculpture across the entire shell, even the protoconch.
(synonyms - Alvania carpenteri, Alvania keenae, Alvania kyskaensis, Alvania montereyensis, Alvania sanjuanensis, Cingula eyerdami)

Victoria, BC
"Alvania dinora" (Bartsch, 1917)
intertidal to subtidal size to 2mm
California to Southeast AK
This is infrequently found due to its tiny size. It has deep suture lines and fine spiral lines. There are no axial lines. The protoconch is smooth.
(A. dinora is now considered an Atlantic-only species - this shell's identification is unknown.)

Vermetidae

off Lopez Island, WA, subtidal Seppings Island, BC

Petaloconchus compactus (Carpenter, 1864)
Compact Worm Snail
intertidal to 50m California to BC size is irregular
This shell forms colonies and attaches to rocks or shells. The growth
is irregular in shape. The tubes are about 3mm in diameter. They can be easily mistaken for some types of calcareous tubeworms.
(previous name - Bivonia compacta)

Barkley Sound, BC
Caecum dextroversum Carpenter, 1857
Western Caecum
intertidal to subtidal size to 3.8mm
northern Mexico to Alaska
This species is rarely found due to its small size.
This shell usually has a white band behind the aperture. It has a fairly smooth surface.
(synonyms - Caecum occidentale, Fartulum occidentale, Fartulum hemphilli)

Family Rissoidae, Barleeidae,

Caecidae & Vermetidae