Marine Plants of Nha Trang' — DAWSON 
445 
Fig. 54. a, b. Me soth amnion caribaeum: a, Upper portion of a tetrasporangial branch, X 75; a small part of a 
male branch bearing two pedicellate antheridial clusters, X 226. c, d, Antithamnion sp.: c, Part of an erect, alter- 
nately branched secondary axis bearing tetrasporangia, X l^\d, an antheridial branchlet, X 171. e,f, Callithamnion 
sp.: e. Upper portion of a percurrent axis with spirally arranged branchlets, X sporangial structure, X 93. 
g, Wrangelia argus: A small part of a fertile axis showing the lateral branchlets and tetrasporangia, X 96. h, Cen- 
troceras clavulatum: A small part of a filament showing the arrangement of the cortical cells and the ring of spines 
at the nodes, X 150. /, Spyridia filamentosa: A small part of a main axis showing the cortication and the base of 
two determinate branchlets, X 80. 
