LICHENS lOI 



89. Pertusaria communis isidioidea Schaer. 



Port Wells, Prince William Sound (Trelease, 969). On moss. 



No. So (Trelease, Sitka) is on the bark of shrubs. The whitish 

 thallus is very smooth. Immature apothecia are present with a 

 lecanorine disk of a yellowish color. 



No. 827 (Trelease, Sitka) is on dead wood. The thallus is very 

 smooth and thin, scarcely evident, of a light pink color. The imma- 

 ture apothecia are single, with a lecanorine disk, the disk being flesh- 

 colored, with a lighter margin. 



90. Pertusaria pocillaria sp. nov. 



Thallus rather thin, creamy white, verrucose, sorediate. Apothecia 

 lecanorine, small, .5 mm. in diameter. Spores colorless, simple, 2-8 

 in an ascus, f-yzfl A'* Paraphyses slender, branched. 



Type specimen in the herbarium of the Missouri Botanical Garden, 

 and a duplicate in my own herbarium ; collected by Prof. William 

 Trelease on Alnus at Farragut Bay, June 5, 1899, no. 806a. 



The species approaches Pertusaria xanthostoma (Sommerf.) Fr., 

 but differs in the distinctly smaller spores. The measurement given 

 for the spores of P. xanthostoma is W\\ (J- 



In many cases the hymenial layer of the apothecium has fallen out, 

 leaving the exciple as an empty cup, a fact which has suggested the 

 specific name chosen. Undoubtedly this fact has an ecological signifi- 

 cance in the distribution of the spores, as M. Miyoshi ' has recorded 

 for Sagedia macrospora. 



The following additional species of the genus Pertusaria are cred- 

 ited to Alaska : P. bryontha (Ach.) Nyl., collected by Wright on the 

 islands of Bering Strait, by Dr. Bean on Unalaska Island, and re- 

 ported by Nylander as collected at Port Clarence, by Dr. Almquist ; 

 P. panyrga (Ach.) Nyl., collected by Macoun on rocks on St. Paul 

 Island and reported by Nylander as having been collected at Port 

 Clarence; P. velata (Turn.) Nyl., collected by Dr. Bean at Warm 

 Springs, Sitka; P. trochiscea Norm., P. subobducens Nyl., P. sub- 

 dactylina Nyl., P. sommerf eldtii (Flk.) Nyl., all collected by Dr. 

 Almquist at Port Clarence; P. subplicans Nyl., P. glomerata cor- 

 niculata Nyl., and P. rhodoleuca Fr. fil., collected on St. Lawrence 

 Island by Dr. Almquist, determined by Nylander. In his correction 



* Miyoshi, M. Ueber die Sporocarpenevacuation und darauf erfolgendes 

 Sporenausstreuen bei einer Flechte. The Journal of the College of Science 

 Imperial University, Tokyo, Japan. 15' : 367-370. /. 18. 1901. 



