162 NEW LICHENS. 
crenatis, lævigatis, rugosis ; gemmis subrotundis ; apothe- 
ciis planiusculis, disco concolori, margine subintegerrimo, 
dorso corrugato. 
Has. Swan River; Mr. James Drummond. — It requires 
attentive examination to separate the present species from 
P. olivacea, Ach. The lobes of the thallus are more elon- 
gated, their surface smooth, never rough with rigid 
points : the margins of the apothecia are quite entire; and 
their under surface is much wrinkled. When moistened - 
the surface of the thallus assumes a yellowish hue. 
3. P. incisa, Tayl.; thallo suborbiculari, levigato, inæqua- 
bili, pallidissime sulphureo, subtus nigricante, lobis incisis, 
sinuatis, margine inæquali adscendente; gemmis margina- 
libus, granulatis, planiusculis; apotheciis sessilibus, mar- 
gine incurvo, tumido, subdiviso, levi, disco concavo, 
fusco. 
Has. Swan River; Mr. James Drummond.—Thallus nearly . 
eight inches wide: margins of the lobes usually blackish : 
. laciniæ imbricated, attached beneath by very short black- 
ish processes. P. liliacea, Ach., it has the lobes morè 
deeply divided; while the pruina on the surface of that 
species as well as the black. fibrils beneath are entirely 
wanting. = 
4. P. scabrosa, Tayl.; thallo suborbiculur, inciso, pallidis- | 
sime sulphureo, subtus nudo, nigricante, lobis elong 
convexis, = € Areni er = 
