118 TEANSACTIONS LIVERPOOL BIOLOOICAL SOCIETY. 



Fronds composed of a single row of cells above, 

 but below with a false cortex formed by the 

 growth of descending filaments given off from 

 the cells 72 



Fronds formed of large cells placed end on end, 

 with bands of smaller cells at the nodes, in 

 some cases the nodal cells extending in a thin 

 layer over the internodal cells 73 



67. Spores on short pedicels distinct undivided ^.. 68 

 Fronds composed of prostrate, creeping filaments 



from which arise erect, dichotomous or irregu- 

 larly branched filaments Bliodochorton 



Both tetraspores and cystocarps present... ... 69 



68. Spores terminating short lateral hrdoWcliQ^Gliantransia 

 Spores axillary ... ... Monospora 



69. Cystocarps terminal, involucrate, spores irregu- 



larly grouped not surrounded by a common 

 gelatinous envelope when mature ... ... 70 



Cystocarps terminal or lateral, spores irregularly 

 grouped at maturity, covered by a general 

 gelatinous envelope ... ... 71 



70. Fronds formed of prostrate filaments from 



which arise erect pinnate filaments Sioermothamniori 

 Fronds pinnate, ramuli whoiied Sphondylothamnion 



71. Fronds dichotomous formed of delicate vesicular ' 



cells, tetraspores in involucrate whorls at the 

 nodes or on the inner side of short fascicled 

 branches ... Griffithsia 



Fronds dichotomous or pinnate, branches alter- 

 nate, tetraspores tripartite, favellae binate, 

 lateral ... Callithamnioji (\\\ ]}djYi) 



Fronds pinnate, favellas terminal, involucrate ; 

 tetraspores polysporic Pleonosporium 



