As far as what's legal and illegal in California:
(7) Class Reptilia -Reptiles
(A) Order Crocodilia -Crocodiles, Caimans, Alligators and Gavials: All species (D).
(B) Family Chelyridae -Snapping Turtles: All species (D).
(C) Family Elapidae -Cobras, Coral Snakes, Mambas, Kraits, etc.: All species (D).
(D) Family Viperidae -Adders and Vipers: All species (D).
(E) Family Crotalidae -Pit Vipers: All species (D), except Crotalus viridis (Western rattlesnake), Crotalus atrox (Western diamondback rattlesnake), Crotalus ruber (red diamondback rattlesnake), Crotalus scutulatus (Mojave rattlesnake), Crotalus mitchelli (speckled rattlesnake) and Crotalus cerastes (Sidewinder) not restricted.
(F) Family Colubridae -Colubrids:
1. Dispholidus typus (Boomslang) (D).
2. Theoltornis kitlandii (Bird or vine snake) (D).
3. All species of genus Nerodia (watersnakes) (D).
(G) Family Helodermatidae:
1. Heloderma suspectum suspectum (reticulate Gila monster) (D).