 across the snake, and you may want to take more than one measurement to make sure that it is going to be legal, that's the safest way to do it, the safest way to measure it. The second is a clear plastic tube. And clear plastic tubes, if you don't know what you're doing, I would not recommend that. It's a lot easier to get bit by the snake. But if you get part of the snake in the clear plastic tube, you're holding the tube, hold the snake, and then you're on a measuring tape along the body of the snake.