426 Arthur and Kern : Peridermium 



yet it appears fairly distinct in most specimens examined. It 

 sometimes forms witches 1 brooms, as in Per. coloradense, and in 

 other characters closely resembles that species. It differs in the 

 leaves usually remaining attached to the branch after drying, in the 

 more prominent pycnia, and in small differences in spores and 

 peridial cells. 



17. Peridermium coloradense (Dietel) nom. nov. 



Aecidium coloradense Dietel, in Engler & Prantl, Pflanzenfam. 



I 1 ** : 78. 1897. 



O. Pycnia amphigenous, numerous, scattered, conspicuous, 

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



globoid or flask-shaped, slightly protruding, 110—150^ broad. 



I. Aecia from perennial mycelium, usually forming witches' 

 brooms often of great size, hypophyllous, forming two irregular 

 lines, flattened laterally, 0.8-1 mm. high, erumpent from a lentic- 

 ular opening, 1-2 mm. long, dehiscent along the sides, the upper 

 part often falling away in pieces leaving a lacerate margin ; per- 

 idium colorless, or pinkish at apex, cells slightly overlapping, 

 walls rather thin, outer smooth, thin, inner thicker, verrucose ; 

 aeciospores broadly ellipsoid or globoid, 16-25 by 26-35 [i, wall 

 colorless, medium and rather unevenly thick, 2-3 //, densely and 

 rather coarsely verrucose ; contents orange-red fading to nearly 

 colorless. 



On Picea Engelmanni (Parry) Engelm., Colorado, August, 1877, 

 T. S. Brandegee (specimens in Crypt. Herb. Harvard University) ; 

 Rocky Mountains, Canada (?), March 8, 1885,/ Macoun (speci- 

 men in herbarium N. Y. Bot. Garden) ; Music Pass, Sangre de 

 Cristo Range, Colorado, July, 1888, Rev. C. H. D erne trio (in Ellis 

 & Everh. N. A. F. no. 222j); Devil's Lake, Athabaska, Canada, 

 March 7, 1891,/ Macoun jf 2; Lower Basin of the Gallatin 

 River, Montana, July 8, 1S98,/. W. Blankinship ; Black's Fork, 

 Wyoming, July 16, 1901, Pammcl, Johnson, Lummis, & 

 Buchanan 664. ; Smith's Fork, Wyoming, August 2, 190 1, L. H. 

 Pammel 638 ; Boulder, Colorado, July 1904, E. Bethel ; Mariposa 

 Dell, Colorado, August 10, 1905, F. E. & E. S. Clements (in 

 Crypt. Format. Colorado, no. 152); Georgetown, Colorado, no 

 date, Wm. Tr el case. 



On Picea Mariana (Mill.) B.S.P. {Abies nigra Desf.), Cacouna, 

 Quebec, Canada, August 10, 1891, D. P. Penhallow (in Seym. 



