Aegires albopunctatus
(1-2,8: San Carlos Beach, Monterey / 3-5: Whaler's Cove, Point Lobos / 6-7: West of Santa Barbara Island)
San Diego Dorid
Diaulula sandiegensis
(1-2,7-8: San Carlos Beach, Monterey / 3: Coral Gardens, San Clemente Island / 4: Flame Reef, Santa Cruz Island / 5: Whaler's Cove, Point Lobos / 6: Monterey State Beach, Monterey)
Usually they have black rings or spots on their backs, but rarely they'll be spotless:
(1: San Carlos Beach, Monterey)
Santa Barbara Janolus
Janolus barbarensis
(1: Arch Point, Santa Barbara Island)
Sea Lemon
Peltodoris nobilis
(1-2,4-5: San Carlos Beach, Monterey / 3,6: Monterey State Beach, Monterey / 7: Monastery Beach, Carmel-by-the-Sea / 8: Whaler's Cove, Point Lobos)
The sea lemon looks similar to the Monterey dorid. However, the sea lemon only has black on its skin, not on its tubercles.
This pair is next to some nudibranch eggs. The lower one is unusually white-skinned; it may be full of eggs and preparing to lay them (or it may just be a mutant...):
(1: San Carlos Beach, Monterey)
This one is eating a sponge:
(1: Monastery Beach, Carmel-By-The-Sea)
Shag-Rug Aeolid
Aeolidia papillosa
(1-6: Monterey State Beach, Monterey / 7-8: San Carlos Beach, Monterey)
These are its eggs (and the back half of the aeolid):
(1: Monterey State Beach, Monterey)
Spanish Shawl
Flabellina iodinea
(1: Coral Gardens, San Clemente Island / 2-4: Eel Point, San Clemente Island / 5: Seal Cove, San Clemente Island / 6-7: Ship Rock, Santa Catalina Island / 8: Monastery Beach, Carmel-by-the-Sea)
Spotted Cadlina
Cadlina sparsa
(1: Whaler's Cove, Point Lobos)
Spotted Triopha
Triopha maculata
(1-4: San Carlos Beach, Monterey / 5,7-8: Monterey State Beach, Monterey / 6: Monastery Beach, Carmel-By-The-Sea)
These are near-perfectly camouflaged in giant kelp, where they lay their eggs:
(1: San Carlos Beach, Monterey)
Three-Lined Aeolid
Flabellina trilineata
(1-2: Monterey State Beach, Monterey / 3: San Carlos Beach, Monterey / 4-5: Whaler's Cove, Point Lobos)
In the 2nd image, the middle nudi is a hermissenda; the top and bottom are three-lined aeolids. The one in the 3rd image is tiny, in the lower center, surrounded by eggs from some other larger nudibranch. The one in the 4th image was floating a few feet below the surface; it's upside down in the 5th image.
White Dendronotus
Dendronotus albus
(1,4-5: Whaler's Cove, Point Lobos / 2: East Pescadero Pinnacle, Pebble Beach / 3: Lovers Point, Monterey / 6: San Carlos Beach, Monterey / 7-8: Monastery Beach, Carmel-by-the-Sea)
White Dorid
Atagema alba
(1-2: San Carlos Beach, Monterey)
White Knight Dorid
Doris odhneri
(1,4,8: San Carlos Beach, Monterey / 2-3,5-7: Whaler's Cove, Point Lobos)
White Smooth-Horn Dorid
Conualevia alba
(1: San Carlos Beach, Monterey)
White-Spotted Dorid
Doriopsilla albopunctata
(1,3: Whaler's Cove, Point Lobos / 2,5-8: San Carlos Beach, Monterey / 4: Flame Reef, Santa Cruz Island)
Usually yellow, but sometimes brown:
(1: Sea Landing Cove, Santa Barbara Island)
This one is laying eggs:
(1: Lovers Point, Monterey)
Yellow Horned Dorid
Acanthodoris lutea
(1-5: San Carlos Beach, Monterey)
Yellow Margin Cadlina
Cadlina luteomarginata
(1,8: San Carlos Beach, Monterey / 2-6: Whaler's Cove, Point Lobos / 7: Monastery Beach, Carmel-By-The-Sea)
Yellow-Spot Cadlina
Cadlina flavomaculata
(1,5: San Carlos Beach, Monterey / 2-4,6: Whaler's Cove, Point Lobos / 7-8: Monastery Beach, Carmel-by-the-Sea)
These are small, less than 1" long.
Nudibranch Eggs
(1-3,8,11: San Carlos Beach, Monterey / 4-5: Whaler's Cove, Point Lobos / 6-7: Flame Reef, Santa Cruz Island / 9: Coral Street, Monterey / 10: Monterey State Beach, Monterey)
Nudibranchs lay their eggs in a spiral, which looks a lot like a flower. Different nudibranchs have different patterns.