EEVISED LIST OF MAEINE ALG^. 119 



Branches opposite or whorled, tetraspores cru- 

 ciate Antithamnion 



Fronds with a monosiphonous axis, partly con- 

 cealed by the densely whorled branches, 

 cystocarps terminal on short branches, tetra- 

 spores in whorls one above another on special 

 branches Haluriis 



72. Fronds capillary or bushy, densely branching, 



cortications confined to the larger branches, 

 and evidently formed of vein-like descending 



filaments CaUithamnion {i\\^2^Ti) 



Fronds compressed, ancipital,branches,pectinate- 

 pinuate, covered everywiiere, except at the tips, 

 by polygonal areolated cells 74 



73. Fronds dichotomous, tips usually incurved Ceramium 

 Fronds pinnate, main branches corticated 



throughout with cells arranged in transverse 

 bands, secondary branches corticated only at 



the nodes Spyridia 



14. Opposite pinn« of equal size, cystocarps ter- 

 minal on the branches, tetraspores solitary 



on the ends of the branches Plumaria 



Pinnae of unequal sizes, one being short and 

 simple the oi3posing one comparatively long 

 and pinnately divided or compound, cysto- 

 - carps on special short pinnae or on the upper 

 margins of the ultimate branches, tetraspores 

 clustered Ftilota 



75. Fronds dark-red or nearly black, substance dense 76 

 Fronds rose-red or purple, rather succulent or 



gelatinous, sometimes capillary 78 



76. Fronds compressed, fringed with minute ramuli, 



cystocarps terminal on the ramuli Sjjhcerococciis 

 Fronds dichotomous, cvlindrical, cartilac^inous 77 



