Art Cottrell (Arthur Cottrell?) and James Cottrell

The sailor on the right is my father, James Calvin Cottrell, of San Angelo, Texas. He appears to have sent this picture to his mother and he wrote the date on the back as well as the following inscription:

Art Cottrell
A second cousin and a swell guy.

The thing is, I don't know of any Art Cottrell nor do any of my Cottrell cousins. Does anyone know who Art Cottrell is?

My father passed away MANY years ago, so there is no chance to ask him. Does anyone know who this Art Cottrell is?