PLATE XII. 



ElG. 



1. Structure of the stylet-region in a large Ampkiporus lactifioreus. The specimen had two 



marginal sacs on one side. X 350 diam. 



2. Structure of the stylet- and reservoir-regions in the same form. Considerably magnified. 



3. Abnormal stylet-region in the same species, a, perfect stylet-sac of the left side ; b, shriveled 



sac of the right side. X 210 diam. 



4. Termination of the posterior chamber of the proboscis (c) of A. lactifioreus, with muscular 



ribands. X 210 diam. 



5. The central (a) and marginal stylets (6) from a young J. lactifioreus, on the first appearance 



of the former. X 700 diam. 



6. Structure of the stylet-region of the proboscis of Amphiporm pulcker. X 90 diam. 



7. Central stylet-apparatus of the same species, a, central stylet; b % reserve-stylet in situ. 



X 210 diam. 



8. Structure of the stylet-region in Tetrastemma melanocep/iala, X 90 diam. 



9. Structure of the stylet-region in Tetrastemma flavida, with the reservoir somewhat contracted. 



X 210 diam. 



10. Extremity of the posterior chamber of the proboscis of Tetrastemma dorsalis, apparently after 



rupture of the muscular ribands from the sheath of the organ. X 350 diam. 



11. Structure of the stylet-region of the proboscis in Nemertes gracilis. X 210 diam. 



12. Structure of the stylet-region of the proboscis of Nemertes Neesii. X 210 diam. 



13. Portion of the posterior chamber of the proboscis of the same species, showing the charac- 



teristic plaits of the mucous surface. X 90 diam. 



14. Structure of the stylet-region of the proboscis of Nemertes carcinophila. X 700 diam. 



