432 THE RUSTS OF NOVA SCOTIA. FRASER. 



Peridermium (on Tsuga). Puccinistrutn Myrtilli 

 (Schum.) Arth. 



The connexion of the following form has not yet been 

 established : 



Per. balsameum Peck. 



Two other species may occur in Nova Scotia, Per. color- 

 adense (Diet.) Arth. & Kern, and Per. Laricis (Kleb.) Arth. 

 & Kern. The former has been collected in Maine. It forms 

 witches 7 brooms on Picea and is conspicuous. The latter has 

 not been collected in North America, but as the telial form on 

 Betula [Melampsoridium Beiulae (Schum.) Arth.] is rather 

 common, it will doubtless be found also. 



Peridermium balsameurn Peck. 



0. Pycnia hypophyllous, few, scattered, honey-yellow, 

 small. 



1. Aecia hypophyllous, in two irregular rows on yellowish 

 areas occupying all or part of the leaf, white, mostly cylindrical, 

 amall, opening at apex; peridium colourless, margin erose or 

 somewhat lacerate. Aeciospores ellipsoid or globoid, 15-22 by 

 19-27/A, wall thin, densely verrucose ; contents colourless. 



On Abies lalsamea (L.) Mill., Pictou, July 15, 1909; 

 fccotsburn, August, IT, 1909; Folleigh Lake, August 31, 1919. 



This species is characterized by its white spores, no other 



Peridermium in Eastern North America shows this character. 



It may be identical with the European Aecidium pseudocolum- 



nare Kuhn, which also has white spores, (See note Arthur & 



Kern, Bull. Torr. Bot. Club 33:436. 1906). 



From field study the writer is convinced that Peridermium 

 balsameum is the aecial stage of some species of the genus 

 Uredinvpsis. Probably several species are confused under this 

 Peridermium. 



