He is
all Maine Coon I think! Anyone who has ever had a Maine Coon Cat should recognize it. The beautiful feathery fur, long bushy tail, the hind profile, and the utter lack of awareness of one's own size and shape, and somewhat naughty inquisitiveness indicates Maine Coon to me. Mr. Tappy, when he was alive, always displayed a willingness to shove himself into any possible confined space -- as far as he was concerned he was a pair of eyes, a point particle that could occupy any and all space and could fly through the air with ease (not really -- many disasters) as he explored the reaches of the known universe. This guy Marty seems to have the same Maine Coon thing.
-Dr. Wu