ClipArt ETC
"1, 2, left, two tracheal rings, separate. b; 1, 2, right hand, the same put together." Elliot Coues, 1884

The Tracheal Rings of a Bird

"1, 2, left, two tracheal rings, separate. b; 1, 2, right hand, the same put together." Elliot Coues,…