MARINE ALGJE OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 83 



DESCRIPTION OF PLATES. 



(Figs. 1-6, 8-19 are reproduced from Journ. of But. ; and Fig. 7 from the Report of the National Antarctic 

 Expedition by kind permission of the Editor of the Journal of Botany and the Trustees of the 

 British Museum respectively.) 



* 



Fig. 1. Monostroma endivixfolium. Portion of plant, nat. size. Fig. 2. Caudate basal cells, seen in 

 surface view, x 150. Fig. 3. Ditto, seen in longitudinal section, x 150. Fig. 4. Upper part of thallus, 

 transverse section, x 150. Fig. 5. Ditto, surface view : it, showing cells in twos and fours shortly after 

 division ; and b, when they are more evenly distributed, x 150. 



Fig. 6. Pliyllogigas simulants. Longitudinal section of lamina, showing central strand of hyphfe, with 

 one '' trumpet-hypha " in longitudinal, and one in transverse view, x about 150. The cells of the external 

 layer are in reality quadrate, thin-walled, with granular contents, and not, as shown here, rotundate ami 

 densely obscured. Fig. 7. Outer part of longitudinal section of stipes, representing the cortex composed of 

 short perpendicular rows of small quadrate cells, which, passing inwards, change gradually into a pluriseriate 

 subcortex of large round and oblong cells, which in turn merge into the medulla; this latter is composed of 

 densely packed straight hyphoe ; only the external part of the medulla is shown, x 110. 



Fig. 8. Callophyllis varieijata '! Transverse section of thallus, showing endophyte, x 288. 



Fig. 9. Gracilaria simple*. Transverse section of fertile frond, showing tetrasporangia, x 288. 

 Fig. 10. Outline of a sterile frond with eroded apex, nat. size. Fig. 11. Transverse section of thallus of same : 

 ii, taken from margin, showing thick-walled cells; b, taken from middle of frond, where the cells have 

 much thinner walls. In b may be seen filaments of Entonema creeping over the cell-walls, x 150. In 

 fig. 11 the walls of the large interior cells are represented as two to four times as thick as they should be. 

 The largest of the interior cells have a diameter of 200 /x.. The cortical cells measure 12-15 ^ long by 

 6-10 /j. thick. 



Fig. 12. Hydrolupatlnim stephanocarpum. Portion of plant, nat. size. Fig. 13. Cystocarp, x 30. 

 Fig. 14. Section of cystocarp sessile on sporophyll, x 30. 



Fig. 15. Pteridium pruUferu/ii. Branch showing proliferations from margin and midrib, nat. size. 

 Fig. 16. Tetrasporic branchlet with growing points, and showing, not cortex, but interior tissue, x 30. 

 Fig. 16A. Apex of lobe, surface view, x 150. Fig. 17. Tetrasporangia, surface view, showing their 

 subcortical position, x 350. 



Fig. 18. Floridea. Transverse section of thallus, x 44. Fig. 19. Portion of same, showing cortex 

 and interior cells, x 288. 



