128 PLANARIA. 



PLATE XVI. 



FIG. 1. Planaria gravata ? 



2. The same, enlarged. 



3. Planaria hebes. 



4. The same, enlarged. 



5. Planaria lactea, abstinent. 



6. The same, having fed, back. 



7. Belly. 



8. Head, enlarged. 



9. Supposed ovum. 



10. Planaria arethusa, adult, dark grey. 



11. Specimen, adult, brown. 



12. Head of a grey specimen. 



13. Specimen, compressed, enlarged. 



14. Extremity of fig. 10, regenerating the anterior part. 



15. The same, become an entire animal. 



1 6. Anterior section of fig. 1 J , regenerating the part defective. 



17. Anterior section of another portion, regenerating the posterior part. 



1 8. Middle section of the same specimen, regenerating the defective an- 



terior and posterior parts. 



19. Posterior section of the same specimen, having regenerated the de- 



fective anterior. 



20. Planaria wariegata, enlarged. 



21. Planaria alba, enlarged. 



22. Head, more enlarged. 



23. Planaria gracilis. 



24. Planaria algce, enlarged. 



25. Head, more enlarged. 



26. Planaria falcata, enlarged. 



27. Anterior portion, more enlarged. 



28. Another specimen, shewing the internal organization, enlarged. 



29. Another specimen, enlarged. 



30. Planaria stagni, enlarged. 



31. Planaria fcecunda, enlarged. 



32. Planaria flustr&, enlarged. 



33. Planaria vorax. 



34. The same, enlarged. 



