No. 8. MONOGRAPH OF THE NORWEGIAN PHYSCIACEAE. 83 



Thallus growing in small rosettes, diam. i 1,5 cm. Laciniae nar- 

 rowly filiform, 0,050,15 (0,2) mm. broad, distinctly flattened, with 

 an irregular, undulate or even crenate margin, very multifid, either 

 pinnate or divaricately furcate, greatly entangled in each other. In young 

 plants they are appressed to the substratum and 

 (indistinctly) stellate, later they become imbricate 

 and more or less ascending or even erect at the K~~V<; ; 



centre, old thalli pulvinate. Thallus very JlJ VvS 

 fragile, surface minutely scabrose (strong lens), *'*, Hfe 



opaque, moistened translucent, at the margin fel^j^v '^v^ V-Q 

 of the old laciniae with short, round, %^ \ 



coralloid isidia of the same colour as the /' *~"t -*> 



thallus. If the cortex of the isidia break off, ^JF^I* 

 marginal hyphae sometimes grow forth, forming Fig. g. 



small, inconspicuous, white secondary soredia. ph y scia tremulicola. Nyl. 

 Colour dark brownish to black, lower side and rhizinae 

 originally pale, later the rhizinae and the adjacent parts 

 of the cortex become darker or even black. 



Upper cortex up to 20 ,u thick, formed of thin- walled, constrictedly sep- 

 tate hyphae (up to 8^ thick), perpendicular to the surface and sometimes 

 growing forth as hair-like pellucid emergences. Cortex dark at the exterior 

 part, otherwise uncoloured. Gonidia conglomerate, arranged in an irregu- 

 lar stratum under or in the cortex, sometimes at the very surface of the 

 thallus. Medulla white. 



Apothecia unknown, pycnides searched after but in vain. 



React. Cortex and medulla uncoloured by KOH as well as by 

 CaCl 2 O 2 . 



Hab. Recorded only from the bark of Populus tremula. 



Loc. The locus classicus of the species is Dovre (ZETTERSTEDT). 

 Otherwise it is only recorded from Vaage: Presteberget (HAVAAS), and 

 from Hakedalen, near Kristiania, not far from the railway station. (HAV- 

 AAS and LYNGE). It has been much searched after in our country and 

 must be a rare species. 



WAINIO described a new Physcia: Ph. pterygioides^, evidently sepa- 

 rated from Ph. tremulicola by the colour: cinereus, subtus albidus, tre- 

 mulicola is after NYL. 1. c. olivaceo-fuscus, . . . subtus concolor. 

 The authentic specimen of Ph. tremulicola NYL. (herb. Ups.) is pale greyish- 

 brown (faded?), under side uncoloured. I have not seen Ph. pterygioides. 



1 WAINIO: Lich. Viburg. Meddel. Soc. Fauna et Flora Fennica vol. II (1878) p. 53. 



