432 THE RUSTS OF XOVA SCOTIA. — ERASER. 



Peridermhnn (on Tsuga). — Fncciuistnnn MyrtlUi 

 (Schum.) Artli. 



Tile c'oiinexiuii of the following form has not yet been 

 established : 



Per. balsameum Peck. 



Two other species may occur in I^ova Scotia, Per. color- 

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

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

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

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

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

 common, it will doubtless be found also. 



Peridermium balsameum Peck. 



0. Pycnia hy])0];)hyllous, few, scattered, honey-yellowy, 

 small. 



1. Aecia hypophyllous, in two irregular rows on yellowish 

 ai^as occupying all or part of the leaf, white, mostly cylindrical, 

 arnalJ, opening at apex; pcridium colourless, margin erose or 

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

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



■ On AUcs balsnmea (L.) Mill., Pictou, July 15, 1009; 

 Scotsbnrn, August, 17, 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 33:430. 1906). 



From field study the writer is convinced that Peridermium 

 halsaineum is the aeoial stage of some species of the genus 

 Vredinopsis. Probably several species are confused under this 

 Peridermium. 



