finding files in a dir

Question

I have a directory with a lot of files inside:

pic_1_79879879879879879.jpg
pic_1_89798798789798789.jpg
pic_1_45646545646545646.jpg
pic_2_12345678213145646.jpg
pic_3_78974565646465645.jpg
etc...

I need to list only the pic_1_ files. Any idea how I can do? Thanks in advance.