138 R. C. PUNNETT. 



Pig. 1, a — d. — Eupolia melanogramma. Transverse sections, illustrat- 

 ing the arrangement of the blood-vessels iu the region of the brain, x 45. 



Fig. 2. — E. melanogramma. Portion of a transverse section, showing an 

 excretory tubule opening into the oesophagus, x 110. 



Fig. 3. — E. melanogramma. Showing an excretory duct piercing the 

 lateral nerve-cord. x 110. 



Fig. 4. — E. melanogramma. Transverse section, showing ventral position 

 of anal commissure. X 60. 



Fig. 5. — E. melanogramma. Transverse section of body-wall in oeso- 

 phageal region. X 110. 



Fig. fi. — E. pliolidota. Transverse section through brain just behind the 

 commissures. X 45. 



Fig. 6a. — E. pliolidota. Transverse section through cerebral organ and 

 neighbouring structures. X 45. 



Fig. 7.— E. pholidola. Dorsal view of anterior end. x 2. 



Fig. 8. — E. pliolidota. Transverse section through outer body- wall in 

 the oesophageal region. X 160. 



Fig. 9. — E. pliolidota. Transverse section through anterior portion of 

 intestinal region. X 45. 



Fig. 10. — E. pholidota. Portion of a section from about the same level 

 as the preceding, but more highly magnified, x 



Fig. 11. — Cerebratulus natans. From spirit specimen. Natural size. 



Fig. 12. — C. natans. Anterior extremity, showing pigment patches. 

 From a formol specimen. Natural size. 



Fig. 13. — C. natans. Transverse section of proboscis, x 45. 



Fig. 14. — C. insignis. Anterior end. x |. 



Fig. 15. — C. natans. Transverse section through intestinal region. X 32. 



Fig. 16. — C. robustus. Section through one of the oesophageal folds. 

 X 110. 



Fig. 17. — C. bedfordii. Transverse section through proboscis, x 45. 



Fig. 18. — C. bedfordii. Section through snout, x 45. 



Figs. 19 — 26. Sections through the outer portion of the body-wall in the 

 oesophageal region. All X 160. 

 Fig. 19. — C. brunneus. 

 Fig. 20.— C. robustus. 

 Fig. 21. — C. natans. 

 Fig. 22.— C. erythrus. 

 Fig. 23.— C. sordidus, 



