Thanks, everyone. Mrspunkysmom, yes, they are named for Simon and River from "Firefly" and "Serenity."

In the last few minutes, Simon has climbed the (still undecorated) Christmas tree, and River has run across the piano and played a tune. It is fun having kittens, but it is a totally different world from the senior kitty world we have lived in in recent years. Love it, though!