ILLUSTRATIONS 



Our Face from Fish to Man . . Frontispiece 



1. Devonian shark, Cladoselache; 2. Upper Devonian 

 air-breathing, lobe-finned fish, Eusthenopteron; 3. Lower 

 Carboniferous amphibian, Eogyrinus; 4. Permo-Carbon- 

 iferous reptile, Seymouria; 5. Triassic mammal-like 

 reptile, Ictidopsis; 6. Cretaceous mammal, Eodelphis; 

 7. Lemuroid primate, Propithecvs; 8. Recent Old World 

 monkey; 9. Chimpanzee; 10. Tasmanian; 11. Roman 

 athlete. 



FIGURE 



1. — The First Mouths ..... 5 



A. Slipper animalcule (Paramacium) with gash- 

 like mouth. 



B. Jellyfish (Tessera), a two-layered sac with 

 primitive mouth. 



(Both after Parker and Haswell.) 



2. — Two Early Stages in the Evolution of a 



Head . . . . . facing 6 



A. Flatworm (Planaria), showing head-and-tail 

 differentiation, including the beginnings of a brain and 

 of eyes. 



B. Sand-flea (Orchestia), showing the interrelations 

 of eye, brain, mouth, leg-jaws and nerve cord. 



(Both after Parker and Haswell.) 



3. — The Rise of the Vertebrates in Geologic 



Times 9 



4. — Some of Our Earliest Known Kinsfolk: 

 Upper Silurian and Devonian Ostraco- 

 derms ....... 11 



A. Pterolepis. (After Kiaer.) 



B. Tremataspis. (After Rohon.) 



