You can see its loooong tail actually dragging on the ground. Here is the story, as told by Lynne.

“It was an incredible sighting. I had arrived home about an hour before and was entertaining guests. I have glass French doors opening to the front yard and as I came into the room I could see a large, buff-colored feline sunning himself on a PG&E box! His tail was quite long and thick, but you could tell he was a juvenile Mountain Lion because of his enormous tail, size, dark markings on his cheeks and some fading spots on his coat. We opened the front door to get a better look and take some photographs and watched the animal walk for a bit. The Cougar seemed to be distracted, watching us and what turned out to be a neighbor’s house cat. Truffles, also called ‘Saddam’ because she takes on anything and everything, entered the picture and started to stalk the young Mountain Lion. She ultimately tried to attack the Mountain Lion and they moved off into the brush and out of sight but you could hear the yowls of fighting cats. ‘Saddam’ survived, albeit a little shaken, and I haven’t seen the beautiful Mountain Lion since.” 

To see Lynne's other photo showing Truffles, here's the link: http://www.mendonomasightings.com/2012/09/28/a-house-cat-stalking-a-mountain-lion-strange-but-true/

Thanks to Lynne for sharing her sighting and photos with us here.