PLATE 11. Diatomacese. 



[The figures represent the prepared frustules or valves, except when otherwise stated.] 



1. Pinnularia nobilis, side view. 



2. Pinnularia viridis, side view, with endochrome. 



3. Pinnularia oblong a, side view. 



4. Pinnularia radiosa, side view. 



5. Pinnularia radiosa, front view. 



6. Navicula cuspidata, side view. 



7. Navicula cuspidata, front view. 



8. Portion of the valve of a Navicula, showing the transverse rows of dots. 



9. Navicula didyma, side view. 



10. Gyrosigma balticum, side view. 



1 1 . Hoop of the same, side view. 



12. Gyrosigma strigile, side view. 



13. Gyrosigma hippocampus, side view. 



14. Gyrosigma acuminatum, side view. 



15. Gyrosigma attenuatum, side view. 



16. Gyrosigma attenuatum, front view. 



17. Gyrosigma Spencerii, side view. 



18. Gyrosigma lacustre, side view. 



19. Gyrosigma littorale, side view: 



20. Gyrosigma distortum, side view. 



21. Gyrosigma fasciola, side view. 



22. Gyrosigma macrum, side view. 



23. Gyrosigma prolongatum, side view. 



24. Gyrosigma tenuissimum, side view. 



25. Gyrosigma formosum, side view. 



26. Gyrosigma decorum, side view. 



27. Gyrosigma obscurum, side view. 



28. Gyrosigma speciosum, side view. 



29. Gyrosigma strigosum, side view. 



30. Gyrosigma rigidum, side view. 



31. Gyrosigma elongatum, side view. 



32. Gyrosigma delicatulum, side view. 



33. Gyrosigma angulatum, side view, a, with endochrome ; b, variety /3 ; c, variety y, 



end of. 



34. Gyrosigma quadratum. 



35. Gyrosigma cestuarii. 



36. Gyrosigma intermedium. 



37. Gyrosigma transversale. 



38. Gyrosigma transversale. 



39. Portion of valve of 6r. balticum. 



40. Portion of valve of 6r. strigosum. 



4 1 . Portion of valve of G. angulatum. 



42. Portion of valve of G. littorale. 



43. Stauroneis phcenicenteron, side view. 



44 . Stauroneis pulchella, side view. 



45. Stauroneis pulchella, front view. 



46. Stauroneis pulchella, portion of valve. 



47. (The fig. beneath fig. 41, erroneously numbered 43.) Portion of Isthmia enervis. 



48. Portion of valve of Gyrosigma strigosum. 



