Bemes are fundamental, transmissible, mutate-able units of beingness very much in the spirit of memes. The difference is that memes are culturally transmissible elements that have common cultural meanings whereas bemes are highly individual elements of personality, mannerisms, feelings, recollections, beliefs, values, and attitudes.
Bemes do not evolve in an extended evolutionary process today - but in the future, they could do.
I've previously referred to a similar concept by the term "intracranial memes".
Neither my terminology nor Rothblatt's is ideal since - for one thing - these entities don't normally reproduce and evolve. When eventually they do, a "replicator" label may become more appropriate - but at that stage, this should probably still be "meme".