Castle. — Rhynchobdellidce. 



PLATE 3. 



Fig. 7. G. stagnalis. Parasagittal section of anterior part of bod}'. X 96. 



Fig. 8. G. stagnalis. Brain viewed from left side. Reconstructed from sections. 

 X 208. Roman numerals designate segmental nerves; Arabic numerals, 

 the ganglionic capsules which supply nerve fibres to same. 



Fig. 9. G. stag/ialis. Posterior part of ventral ganglionic chain, dorsal view, 

 reconstructed from frontal sections. Arabic numerals designate ven- 

 tral ganglionic capsules ; Roman numerals, metameric nerve bundles. 

 X 170. 



Fig. 10. G. stagnalis. Diagram showing the arrangement of ganglionic capsules 

 on the ventral surface of brain. 



Fig. 11. G. elegans. Dorsal view of brain. 



Fig. 12. G. stagnalis. Dorsal view of anterior part of brain. From frontal sec- 

 tions combined. X 167. 



