my $string = "foo.bar.foobar";
my $count = 2;
my @splits = reverse map {scalar reverse} split(/\./,reverse($string),$count);
# --> @splits = qw/ foo.bar foobar /

$string = "foo.bar.foobar.baz.biff";
$count = 3;
@splits = reverse map {scalar reverse} split(/\./,reverse($string),$count);
# --> @splits = qw/ foo.bar.foobar baz biff /