THE RUSTS OF NOVA SCOTIA. ERASER. ^77 



This species is composed of distinct races. In this vicinity 

 the form on S. patens infects Spergularia, that on S. Michaux- 

 iana and S. glabra alterniflora infects Arenaria. This- has 

 been shown by cultures of the writer. (Mycologia 4:186. 

 1912). In the interior of North America the form on S. 

 Michauxiana infects Polemonium and another form on the 

 ^ame host infects 8teironema. This has been shown by cultural 

 experiments by Arthur (Jour. Mycol. 12:24. 1906). 



Uromyces Silphii (Svd.) Arth. 

 Uromyces Junci-tenuis Syd. 

 Nigredo Silphii (Desmaz.) Arth. 



0. Pycnia chiefly epiphyllous, in small- groups, golden- 

 brown. 



1. Aecia amphigenous, in groups 4-10 mm. across, 

 crowded about the pycnia on discoloured spots; peridium 

 colourless, margin recurved, lacerate. Aeciospores angularly 

 tfloboid, small, 13-18/u; wall colourless, thin, minutely 

 verrucose. 



II. ITredinia amphigeiious, scattered, roundish or some- 

 what elongated, small, tardily naked, dark cinnamon-brown, 

 ruptured epidermis not conspicuous. Urediniospores broadly 

 ellipsoid .or sometimes obovate, 13-19 by 15-23/*; wall golden 

 yellow, sparsely and bluntly echinulate, pores 5 or 6, scattered. 



III. Telia amphigenous, scattered, roundish or somewhat 

 elongated, small, tardily naked, firm, somewhat pulvinate, 

 blackish-brown, ruptured epidermis noticeable. Teliospores 

 angularly obovate, rounded, truncate or occasionally pointed 

 above, usually narrowed below, 12-19 by 26^35/A; wall chestnut- 

 brown, much thickened above, T-10/x, smooth; pedicel light- 

 chestnut brown, one to one and a half times the length of the 

 spore. 



