114 TEANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



Fronds composed of elongated internal cells, 

 which become smaller at the surface ... 35 



Fronds, at least in the younger portions, formed 

 of cells of nearly uniform length, arranged in 

 transverse bands, without any proper cortical 

 layer 39 



33. Fronds tough and dense Chordaria 



Fronds soft and flaccid 34 



34. Outer cells of cortex producing plurilocular 



sporangia Castagnea 



Outer cells of cortex not producing plurilocular 

 sporangia ... Mesoglcea 



35. Fronds traversed by a central filament formed of 



larger cylindrical cells ... ... ... ... 36 



Fronds destitute of axial filament ... ... 38 



36. Sporangia inconspicuous, formed from the cor- 



tical cells ... ... ... ... ... Desmarestla 



Sporangia conspicuous external ... ... ... 37 



37. Plurilocular sporangia moniliform, attached to 



branching, monosiphonous filaments which 

 form tufted whorls on the hrojuchea... A rthrocladia 

 Unilocular sporangia spheroidal, accompanied by 

 club-shaped paraphyses, in stalked, knob-like, 

 lateral receptacles ... ... ... Sj^orochnus 



38. Frond simple, beset with pellucid hairs, spores 



formed from the cortical cells ... Litosiplwn 

 Fronds branching 39 



39. Unilocular sporangia covering the surface in 



dense patches, at maturity projecting above 

 the surface of the frond ... ... Stictyosiphon 



Unilocular sporangia scattered, immersed Dictyosiplion 



40. Fronds minute, ending in a hyahne hair, mon- 



osiphonous ])elow, densely l^eset above with 



I 



