LIST OF ILLUSTRATIONS 



FIG. 

 I. 

 2. 



3- 



4. 



5- 

 6. 



7- 

 8. 



9- 

 10. 

 11. 

 12. 

 13. 

 14. 

 15. 

 16. 



17. 

 18. 

 19. 

 20. 

 21. 

 22. 



23. 

 24. 

 25. 

 26. 

 27. 

 28. 

 29. 

 30. 

 3i. 

 32. 

 33- 

 34- 

 35- 

 36. 

 37. 

 38. 



39- 

 40. 



41. 



Schematic chordate showing gill-slits ..... 3 



Section through typical chordate ..... 3 



Amphioxus, general view ....... 6 



Amphioxus, anterior end ....... 7 



Amphioxus, hinder end ....... 9 



Amphioxus, vascular system ...... 9 



Amphioxus, section through endostyle .... 10 



Amphioxus, section through gill-bars ..... 10 



Amphioxus, nephridia . . . . . . .11 



Amphioxus, transverse sections ...... 14 



Petromyzon, general view . . . . . . .21 



Petromyzon, anterior region of adult . . . . . 21 



Petromyzon, anterior region of Ammoccete . ... 21 



Origin of chordate eyes . .... 23 



Petromyzon, section through brain ..... 25 



Petromyzon, endostyle of Ammoccete ..... 29 



Method of kidney formation in chordates .... 32 



Petromyzon, urinogenital aperture and anus ... 34 



Scyllium, general view ....... 38 



Scyllium, section through skin . . . . • 39 



Scyllium, auditory sac ....... 40 



Scyllium, section through brain ...... 42 



Scyllium, ventral view of brain ...... 43 



Scyllium, cranial nerves ....... 44 



Scyllium, skull and visceral arches ..... 48 



Scyllium, pectoral and pelvic girdles ..... 50 



Scyllium, alimentary system, and afferent branchial vessels . 52 



Kidneys in Gnathostomes ....... 54 



Scyllium, male urinogenital system ..... 56 



Scyllium, female urinogenital system ..... 57 



Scyllium, venous system . . . . . . • 59 



Scyllium, arterial system ........ 60 



Gadus, general view ........ 65 



Gadus, skull and pectoral girdle ...... 67 



Gadus, palato-pterygo-quadrate ...... 68 



Gadus, neurocranium ....... 69 



Gadus, dorsal view of skull ...... 70 



Gadus, dissection ........ 76 



Ceratodus, general view ....... 80 



Ceratodus, skeleton of pectoral fin . . . . .83 



Ceratodus, lung, heart and vascular system .... 84 



