FLORIDEyE. 127 



are slender and elongated, and consist of a single row of 

 elongated cylindrical cells. From the distal end of each 

 cell numerous slender lateral branches are given off, which 

 branch and form a dense whorl. Each lateral branch gives 

 origin to a branchlet close to the point of origin from the 

 parent axial cell, and these first branchlets, instead of spread- 

 ing outwards to form the whorl, grow downwards and closely 

 pressed to the axial cell, which by this means becomes corti- 

 cated, or covered by closely adpressed branchlets, which 

 continue to elongate downwards for a considerable dis- 

 tance, passing between the branches forming the whorls 

 situated lower down the stem. By this method of cortica- 

 tion the original axial cells forming the lower portion of a 

 long branch are completely covered and consequently 

 strengthened by the descending branchlets, while towards 

 the tip or apex the axial tells are still visible or only 

 partly covered by the descending branches. This method is 

 further developed in the marine genus Ceramium, where the 

 long slender branches consist — as in Batrachospermum — of a 

 single row of large, cylindrical, superposed cells. The lateral 

 branches that spring from the distal end of each cell do not 

 spread out, as in Batrachospermum, but remain closely 

 adpressed to the axial cell, and differ from the corticating 

 cells of the last-named genus in developing both upwards 

 and downwards, consequently covering the distal end of the 

 axial cell producing them, and the proximal end and the 

 axial cell immediately above. In some species, as Cera- 

 mium ruirum, the cortical branches originating from distinct 

 cells meet'and completely cover the axial cells ; in others, as 

 C. ciliaium, the cortication extends only for a short distance 

 upwards and downwards from the point of origin, leaving 

 the central portion of each axial cell naked. 



