Riding my bike northbound on the Colchester spur of the Airline Trail on Sat 5/19/12 at about 6:00PM - a beautiful warm evening. I was slightly north of the Rt 85 crossing, when off in the distance, maybe 200 or more yards ahead of me I saw a large cat like creature cross the trail at a leisurely walk. The thing I noticed was that it was big - maybe slightly larger than a large German Shephard or Collie, and that it had a distinct cat like profile and it had a long droopy slightly curving tail. I only saw it for a second, and at that distance I didn't think it saw me. In the second that my brain was trying to assimilate what it had just seen, my first reaction was a small deer, but I couldn't resolve the visual disconnect with the long droopy gently curving tail. I also thought it was an odd color for a deer, like more dark brown/reddish than lighter brown tan. I passed it off as a deer, figuring that my head was "interpreting" for me. I did look back over my shoulder more often however, on the ride back to East Hampton. I am trully hoping that it was real, and if so, I'm very thankful to have seen it. I'm not too worried about safety, I think those cats are elusive to humans for lots of good reasons (as they see it). If this were grizzly bear country however, I would not have been out there riding alone!