TILE BOTANY OF THE SOUTH ORKNEYS. 29 



EXPLANATION OF THE PLATE. 



P/(ii-/i/lii/ii/ ref/ale, Wainio. 



Fig. 1. An upright podetium showing the small knob-like assiinilators, which, at the top, <; form the roof, 

 whirli gives this lichen a crustaceous appearance, a, substratum; 1>, protothallus ; c, top of 

 P'ulrtiuin. x 8. 



'2. Longitudinal section of a similar poiletium, showing the distribution of the gonidia, g, in the rounded 

 projecting assimilatnrs. in, medullary, c, cortical portion, </, gonidia. x 12. 



