She might have been any other 19-month-old girl. She was dressed in an orange-and-black Halloween jumper and said "Trick or treat" as her mother held her. But this was a news conference Thursday at Midland (Tex.) Memorial Hospital, the first public appearance of Jessica McClure since she was rescued Oct. 16 after being trapped 58 1/2 hours in a well. "I can't explain what it's like to one day think you've lost your daughter, and a matter of weeks later see her smiling and saying, 'Da, Da,' " said her father, Chip McClure, who thanked the more than 400 volunteers involved in her rescue. And then Midland held a parade to thank them, too. From a hospital window, Jessica watched the progress of marchers with pink balloons and ribbons, two marching bands, a float bearing a six-foot square get-well card signed by almost 20,000 people, another flatbed trailer piled with stuffed toys from well-wishers and a sign reading "We're tickled pink," and, to great cheers from the crowd, the large, green "rat-hole" drill used in the rescue. The parade wound about 1 1/2 miles from the hospital to a downtown plaza, where the Hispanic Chamber of Commerce handed out pieces of a pink, 360-pound angel food cake that proclaimed, "Thanks, y'all."