Missing Cat

I am missing my calico. Haven't seen her since early Saturday afternoon. I opened the cat door after breakfast and both left. Normally, I bring them in at night and close the cat door. I've only seen one - her brother - since then. He's following his normal routine, except that he's been more needy the past couple of days. They fought like brother and sister, but I think he's missing her, too. 

I've walked around outside for a distance of several houses, far past where she usually goes. No sign. 

I was hoping to check at the animal shelter - not far from my house - this afternoon but I am having an irritable bowel attack and not fit to drive or hold an intelligent conversation. Hopefully tomorrow. I doubt she's there; they rarely pick up cats and not on weekends, and Patches was not the sort of cat to go to a stranger. I'll still check.