PLATE IX. 



Fin. ].. Viiuti'hyr<i bminiln Solla<. J nat. size, p. (!. 



Fin. 2. Vertical section through an osc-ule ( x 5). 



Fir;. 3. Young specimen with one porocalyx in front and one oscule at the upper end ( X 8). 



Fi<;. 4. Cortical oxea from a large specimen (x 1<>0). 



FK;S. 5-7. Single and double "silica pearls"' (x TIHIJ. 



FICJS. 8-12. '' Silica pearls" around which crystals of sea-salts have become deposited ( X 42f>). 



Fios. 13, 14. Spheroidal masses of sea-salt crystals (in optical section), which stain deeply in carmine 



(X 425). 

 Fie. l.j. Cittnit'll/i xtti/itttt var. inirroxignm. vertical section of cortex in poral region, showing radial cortical 



oxeas aivhing over sub-dermal spaces (x 12). 

 Fie. 16. franieUfi niiijiltn var. i<<'rom't/>n<t, vertical section of cortex in oscular region showing absence of 



radial cortical oxeas (x 12). 



FIG. 17. Cru/iifllii xiiiiitto- var. piichyrrlnibdiix. rlagelluted chambers (x 200). 

 Fins, is, 111. Collar cells of the same (x 1'JOO). 



NOTE. The flagellated chambers as seen in tig. 17 are nearly denuded of collar cells, which 

 have probably become separated owing to the action of the osmic acid used in the case of this 

 specimen : consequently the collar cells with their collars, as seen in the figures, have probably not 

 become fixed in their normal position. See remarks on p. 4. 



