Well, you're in New Mexico...could be a sidewinder, especially since you say the head is NOT "pointy"....and since sidewinders are rattlesnakes, you've got a spot of bother.
Always wondered over threads like this, by the way - during these times of extreme stress, why do some people jump on the computer?....and then NOT go to Google to try and ID the problem?
Maybe not under "Extreme stress" (In which case I would probably shoot and run and then surf LATER anyway), but I often use Free Republic as my main source for information.
Call me lazy but it works damned well.