538 BULLETIN OF THE BUREAU OF FISHERIES. 
ee’. Frond horizontally expanded forming small, more or less definite, disk-shaped spots 
on the substratum. ........ RE tae Se (683 
g’. Frond thin, epssistiie & a single uniform: dave laeget éells preset amone eae 
nary cells; conceptacles small........... ewe! . .MELOBESIA (p. 523). 
gg’. Frond fairly thick, dilereniiated into a ‘thin ‘cil lever ands a thicker upper 
one; cells of fairly uniform size; conceptacles large..... Soe Gh DERMATOLITHON (p. 524). 
eee’. Frond forming indefinite expansions over the substratum. .............00 000 ccc cece eee h’. 
h’. Tetrasporangial conceptacles opening by a separate pore for each sporangium 
RE See aN tele SMe RC Te ist akatale cha cf ae ta Maiev ar fataib solavc sMetate Ae MEDS . -LITHOTHAMNIUM (p. 524). 
hh’, Tetrasporangial conceptacle opening by a single apical pore........ LITHOPHYLLUM (p. 525). 
