Arthur and Kern: Peridermium 425 



which consists of a regularly globose swelling 3 cm. in diameter, 

 on a branch 1 cm. thick at a point where three smaller branches 

 arise. Its gross appearance is similar to Per. Cerebrum, but it is 

 readily distinguished from this and all other known forms on 

 branches, and especially from Per. Strobi Kleb., the aecial stage of 

 Cronartium ribicola, by the remarkably elongate and attenuate 

 peridial cells, placed radially. 



16. Peridermium boreale sp. nov. 



0. Pycnia amphigenous, numerous, scattered, conspicuous, 

 punctiform, honey-yellow becoming blackish-brown, subepidermal, 

 flask-shaped or globoid, protruding, 95— 140 /i broad. 



1. Aecia from perennial mycelium, dwarfing the shoot and 

 causing the leaves to adhere somewhat when dried, if not too 

 mature, hypophyllous, in two irregular rows, flattened laterally, 

 erumpent from slits 0.5-2.5 mm. long, often confluent, 0.5-1.2 

 mm. high, dehiscent along the sides, upper part often falling away 

 intact, leaving an erose margin ; peridium colorless, or pinkish at 

 apex, cells very slightly or not overlapping, walls rather thin, 

 outer smooth, r. 5—2.5 ft, inner verrucose, 3-4 ft; aeciospores 

 broadly ellipsoid or globoid, 16-22 by 23-32 /i, wall colorless, 

 rather thick, 2-4 ft f densely and rather finely verrucose ; contents 

 orange-red fading to nearly colorless. 



On Picea Parrya?ia (Andre) Parry (P. pnngens Engelm.), 

 southern Colorado, July, 1897, E. Bethel (in Ellis & Everh. 

 Fungi Columbiani no. 14-79), tyP e 5 Gypsum Creek Canon, Colo- 

 rado, August, 1894, C. S. Crandall (in Ellis & Everh. Fungi 

 Columb. no. 8y6 y as on " P. Engelmanni") ; North Elk Canon, 

 Rio Blanco County, Colorado, August 20, 1902, IV. C. Stnrgis ; 

 Harvey Peak, South Dakota, July 28, 1904, C. F. Wheeler, com- 

 municated by E. W. D. Holway. 



On Picea Engclmanni (Parry) Engelm., Argentine Pass, Colo- 

 rado, July 17, 1886 (specimen in herbarium of Missouri Bot. 



Garden, St. Louis) ; 



J 



1903, L. N. Goodding 1430 (as on "P. pungens ") ; Edith Pass, 

 Banff, Canada, July 27, 1901, E. W. D. Hokvay ; Vermilion 

 River Valley, British Columbia, Canada, Aug. 16, 1905, E. W. D. 

 Holway ; Kittitas County, Washington, July-September, 1904, 

 J. S. Cotton, communicated by P. L. Ricker. 



Although the boundaries of this species are not well defined, 



