DETLEFSEN 



Photographs of Female Skulls in Paricnt SpiiCiES and Hybrids. 



15. 9 J, original wild female ancestor of all 17. 9 6J, one-half wild hybrid. 



wild and hybrid animals in these ig^ ^ gj^ one-quarter wild hybrid. 



,^ o , ..f.'^^f""^?"'^^' 19. 9 2d/, one-eighth wild hybrid. 



16. V l-io56, female gumea-piR;. 



