A field guide to snakes such as the nose-horned pit viper and common death adder also curiously includes the Adidas Tangent. Maybe it's because of the shoe's description: "Marked by three stripes on its sides . . . is widely known as a fierce predator." Other "field guide" ads illustrate minerals and rocks, with the Adidas Badrock, and river and stream fish, with the Posydon. Leagas Delaney, San Francisco, created the Adidas advertising, which is running in Europe. Copywriter: Matt Rivitz. Art director: Steve Mapp.