DETLEFSEN 



Photographs of Female Skulls in Parjcnt Species and Hybrids. 



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



wild and hybrid animals in these ly. 9 <?/, one-quarter wild hybrid, 



experiments. ,9 ^ ^,^,,^ one-eighth wild hybrid. 



16. 9 12656, female jjuinea-pig. 



