I'll bet you didn't know that a common characteristic of the four species of venemous snakes* in the US is that they all have "elliptical eye slits, aka "cat's eyes." The important thing, then, is that if you encounter a snake, you need to look it in the eyes to determine if it is deadly or not. If you stare in to a snake's eyes and see that they look more like a human's eyes, then he/she** is your friend.
Mac is no snake, of course. And he's not venomous. He has been known to kill mice and small birds from time to time but he does that primarily because that's what cats do in their spare time. Mac has been part of our family for 13 years now, though he is a sprightly 7 in this photo, taken in 2006.
Canon 5D 1/400s f/3.5 ISO400 135mm
*rattlesnake, cottonmouth, coral snake, copperhead **Only trained herpetologists can determine a snake's gender.