Fish hemoglobins. P.C. de Souza and G.O. Bonilla-Rodriguez. Braz J Med Biol Res 2007; 40(6): 769-778.  

Figure 2. A monomer of lamprey hemoglobin generated by Pymol 0.99 (DeLano Scientific LLC) using the 1F5P.pdb file. The figure shows the globin with its a-chain segments and the heme group.