DASYCLADE^. 37 



nal septa. The wall is very thick and tough, and is evidently seen, under the micro- 

 scope, to be formed of concentric layers, deposited one within another, as in the cell- 

 wall of the CaulerpcB. When a transverse section of a branch is examined, the ring 

 of cell-wall appears as if divided into numerous cells, corresponding in number to the 

 ramelli that issue from it ; the apparent septa of these supposed cells being placed 

 opposite the insertion of the ramelli. This would suggest a structure not very differ- 

 ent from what I have just described ; namely, that the axial tube was not a single cell, 

 but a tube formed by the lateral cohesion of a number of small, cylindrical, longitudinal 

 cells, placed in a circle ; a structure not very different from what occurs in Batra- 

 chospermum. After repeated examinations and dissections I am disposed to think that 

 the appearance of cell-division in the wall is deceptive, and that what look like septa 

 are prolongations inwards, through the wall, of the bases of the ramelli. The inter- 

 nodes of the axial filament are beset with very closely placed whorls of horizontal 

 ramelli, each composed of a primary, and 3 or 4 secondary, clavate cells ; the primary 

 cell issuing from the substance of the wall of the axial tube, and forming the basal 

 portion of the ramellus ; the secondary cells springing from its apex. The primary 

 cell is obconical ; the secondary more clavate, and inflated at the point. Fructification 

 takes place by the transformation of one of the secondary or terminal cells of the 

 ramellus, which is changed into a spherical sporangium, filled (at first) with dense, 

 dark green granular matter, surrounded by a pellucid margin, and raised on a short 

 stalk. Whether it eventually contains spores or only zoospores, I have not deter- 

 mined ; analogy with Dasycladus would lead us to the former inference. The colour 

 of the frond, when growing, is a pleasant, and rather a full, yellow green ; when dry, 

 the calcareous crust fades to a dirty white, and the tufts of byssoid apical fibrills become 

 brown or black, staining the paper to which they adhere. 



Ellis's figures, quoted above, are both characteristic ; and so also is that in Sloane's 

 Jamaica, though rude and without analysis. Lamouroux strangely misquotes, under 

 his C. rosarium, Sloane, Tab. 20, fig. 4, which is a very fair representation, not of a 

 Cymopolia, but of Amphiroa fragilissima. 



Plate XLI. A. Fig 1. Cymopholia barbata ; the natural size. Fig. 2. Apex of 

 a branch, crowned with its pencil of byssoid fibres. Fig. 3. Transverse section of a 

 branch, from which the calcareous shell has been removed. Fig. 4. Small portion of 

 the same, showing a sporangium formed from one of the peripheric ramelli. Fig. 5. 

 Portion of a longitudinal section of a branch, to show the insertion of the horizontal 

 ramelli, and the holes on the inner face of the cell wall. Fig. 6. Byssoid fibres from 

 the apical pencil. Fig. 7. Tips of the same ; the latter figures more or less highly 

 magnified. 



