It's a lucky thing for two rats that they nuzzled the nose of a most kind-hearted woman Tuesday in San Francisco.

Because they did so, the happy rats will be spending Christmas in their new home and watching TV, instead of cooling their little paws at the animal shelter.

That makes 168 rats down, 38 to go.

The animal shelter is awash in rats this week, ever since three huge crates of them were dumped on a front porch on Haight Street by person or persons unknown. The rats were brought to the shelter, where they have taken over a suite on the second floor normally reserved for bunnies, birds and guinea pigs while frantic shelter workers call rat lovers, rat owners, rat support groups, rat do-gooders and anyone else who might have room for another rat.

In the meantime, three of the original 176 rats gave birth, as rats will, to 10 baby rats apiece. That boosted the rat population to 206.

"That's what rats do,'' said chief rat caretaker and apologist Sabrina Simmons. "They're just being rats.''

On Tuesday at high noon, the rats became eligible for adoption by the public. Lindsay duPont and her mother, Lisa, drove all the way from their San Ramon home, looking for just the right rat.

First, they had to run the rat adoption gantlet -- filling out rat forms, answering rat questions and presenting their rat cage for inspection. The rat adoption form has 114 interrogatories, including an entire category titled "hopes and expectations'' for prospective rat owners. Then there's the fee of $10 per rat, which tends to weed out snake owners posing as rat lovers in order to get their hands on something to toss to their snakes.