Billy has a Snooze

Compared with the cats I have shared a house with over the years, Billy is unusual in the positions in which he likes to rest and sleep. He often sleeps on his back, his legs in the air and his head turned to one side like this. Today however he adopted a new position which reminds me a bit of a racoon.
It was his second birthday three days ago. We sang him the birthday song but he didn't take much notice.