PLATE XI 



Fig. i. Nitzschia closterium Wm Smith; cells in valve view. 



Fig. 2. Rliabdonema adriaticum Kiitzing; single cell in girdle view, 



showing internal septa. 

 Fig. 3. Asterionella japonica Gran; cells in a spiral colony, girdle view, 



showing protoplasmic contents. 

 Fig. 4. Navicula membranacea Cleve; cells in ribbon formation, girdle 



view, showing protoplasmic contents; note undulating ribbon-like 



chromatophores. 



Fig. 5. Guinardia flaccida (Castracane) Peragallo; cell in girdle view, 

 showing stellate chromatophores and annular structure of the 

 connective zone. 



Fig. 6. Leptocylindrus danicus Cleve ; cells in girdle view, showing proto- 

 plasmic contents, and intercalary bands of the connective zone. 



Fig. 7. Rhizosolenia Stolterfothii Peragallo ; cells in curved chains, girdle 

 view, showing protoplasmic contents and intercalary bands of the 

 connective zone. 



Fig. 8. Ditto. A large form from warm water. 



Fig. 9. Thalassiosira decipiens Jorgensen; cells united by a central 

 mucous thread, in girdle view, showing contents. 



Fig. 10. Thalassiosira gravida Cleve ; cells in girdle view united by central 

 mucous thread. 



Fig. 11. Thalassiosira condensata Cleve; cells in girdle view united by 

 central thread, showing protoplasmic contents and annular struc- 

 ture of connective zone. 



Fig. 12. Ditto. Cell in valve view. 



Fig. 13. RJiizosolenia robusta Norman; cell end, showing striate conical 

 valve, and the finely areolate annular structure of the connective 

 zone. 



Fig. 14. RJiizosolenia calcar-avis Schultze; cell end, showing curved 

 apex of valve and intercalary scale-like connective zone. 



Fig. 15. Rhizosolenia styliformis Brightwell; cell end, lateral view. 



Fig. 16. Ditto. Cell end, dorsal view. 



Fig. 17. Ditto. Dorsiventral view of juncture of two cell ends. 



