PLATE 17.— Diatomacese. 



Figure 



1. Hyalosira rectangula, front view of connected frustnles. 



2. Isihmia enervis, front view. 



3. Licmophora splendida. b, side view ; c, front view of single frustule. 



4. Lithodesmium unchdatum. a, front view ; b, side view. 



5. Melosira nummuloides, front view. 



6. Melosira varians, front view, a, side view. 



7. Meridion circulare. a, frustnles united into a coil, front view ; b, side view of 



single frustule. 



8. Micromega parasiticum, natural size, b, portion of a filament containing the 



frustules ; c, side view, d, front view of a frustule. 



9. Nitzschia sigmoidea. a, side view ; b, front view. 



10. Nitzschia lanceolata. a, front view ; b, separate valve ; c, side view of frustule ; 



10 d, portion of valve, showing the dots. 



11. Nitzschia longissima. a, side view ; b, front view. 



12. Nitzschia reversa, front view of single valve. 



13. Nitzschia. a, taenia ; b, acicularis. 



14. Odontidium turgididum. a, frustules united, front view ; b, single valve, side 



view. 



15. Orthosira Dickieii. a, front view ; b, side view. 



16. Pododiscus jamaiccnsis. a, side view; 6, front view. 



17. Podosphenia Ekrenbergii. a, front view; b, side view of single frustule. 



18. Rhabdonema arcuatum. a, united frustules, front view ; b, side view of single 



frustule. See also PI. 18. fig. 69. 



19. Rhipidophora paradoxa. 6, front view of single frustule ; c, side view of the same. 



20. Striatella unipunctata. a, front view ; 6, the same ; c, side view. 



21. Surirella gemma, a, side view ; 6, front view. 



22. Surirella bifrons. a, front view ; o, side view. 



23. Synedra radians, a, attached frustules ; b, side view of prepared frustule ; 



c, front view of the same. 



24. Synedra fulgens. a, side view ; &, front view of a prepared frustule. 



25. Synedra capita ta, side view. 



26. Sphenosira catena, a, united frustules, front view ; b, side view of single frustule. 



27. Tabellaria floccidosa . a, united frustules, front view ; b, side view of single 



frustule. 



28. Tetracyclic lacustris, united frustules, front view ; «, side view. 



29. Triceratium favus. a, side view ; b, front view. 



30. Tryblionella seutellum, side view. 



31. Tryblionella gracilis, front view. 



32. Tryblionella gracilis, diagram of transverse section. 



