The snail-eating ground beetles (genus Scaphinotus) are a diverse group in California (see my post for May 21 of last year for a note on S. subtilis). We have several in the Sierra, several more along the coast and a handful in other places. A month ago we were camping near Watsonville (in Santa Cruz County) and I found a small meadow near the campground with a few boards that had been left lying on the ground. I turned some of them over and found two different species, S. ventricosus (the smaller one below at around 13mm long).
and S. striatopunctatus (the larger one in the second picture at around 18mm long).