Hi Peter,
 
I haven't done alot of marine collecting over the years, but in 1976 I spent
three months working at a historical museum on San Juan Island, Washington
State, and collected the tidepools in my spare time.
 
Here's a list of what I collected:
 
        Tonicella lineata       Red-lined Chiton
        Mopalia laevigata
               "       lignosa
               "       muscosa     Mossy Chiton
               "       swanii
               "       ciliata
        Katherina tunicata    Black Katy Chiton
        Haliotis kamptschatkana   Pinto Abalone
        Acmaea mitra      White-Cap Limpet
        Collisella digitalis      Finger Limpet
               "        pelta
        Notoacmea persona
               "        scutum    Plate Limpet
        Margarites pupillus
        Calliostoma ligatum
        Littorina scutulata     Checkered Periwinkle
               "       sitkana     Sitka Periwinkle
        Crepidula adunca   Hooked Slipper  (only attached to Calliostoma ligatum)
        Ceratostoma foliatum  Leafy Hornmouth Murex
        Thais emarginata    Dogwinkle
             "    lima
             "     lamellosa      Frilled Dogwinkle
        Searlesia dira     Dire Whelk
        Amphissa columbiana
        Mytilus californianus
        Modiolus modiolus
        Pododesmus macroschisma   Jingle
 
 
There are a few others, but less commonly found.  Forgive my nomenclature, I
realize some needs updating due to placement changes...hope this is of interest.
 
Ken