LIST OF WOODCUTS. 



FIG. 

 I. 



5- 

 6. 



7- 

 8. 



9- 

 lo. 

 II. 



12. 



13- 

 14. 



IS- 

 16. 



17- 

 18. 

 19. 

 20. 

 21. 

 22. 



23- 

 24. 



25- 



26. 



PAGE 



Pelromyzon marinus. The skull, from the left side .... 3 



The braia-case, from above . 4 



The nasal capsule 5 



Dissection of the anterior part of the body, from the 



left side 9 



The urinogenital sinus and adjacent parts ... . 11 



Transverse section through the branchial region . . . 12 



Transverse section through the abdominal region . . 14 



Transverse section through the caudal region . . . 17 



The brain, from above 24 



Raja nasuta. The skeleton, from beneath 30 



Part of the vertebral column 31 



A trunk vertebra, from the front 32 



Longitudinal section of trunk vertebra .... 33 



A caudal vertebra, from the front . 34 



The gall-bladder and bile-ducts . . 49 



The portal vein . .... 51 



The venous system 53 



Raja batis. Urinogenital organs (male) . 55 



Urinogenital organs (female) . . .... 57 



Raja nasuta. The arterial system 62 



Diagram of the heart and chief blood-vessels ... 63 



The nervous system, from above 71 



Raja iatis. The brain, from beneath ... 73 



Longitudinal section of the brain ... ... -74 



The brain, from the left side 74 



Raja nasuta. Roots of the fifth, seventh, and eighth nerves 75 



