Here's an Indian identified at another website as Spotted Tail:

The man with the upside-down rifle is an Arapaho named Big Cow or "Small Cow Heap". I think this is a Chamberlain or Duhem Brothers photograph, but he was also photographed by Will Soule. Big Cow was reportedly the slayer of Major Elliot at the Washita. Here's a comparison:

— Bob / Buffaloman