THE RUSTS OF NOVA SCOTIA. — FRASER. 371 



The one-oelled teliospore with a single apical germ-pore 

 separates this genus from Puccinia. They are alike in other 

 respects. Though the teliospores and urediniospores are both 

 one-celled in Uromyces they may be easily distinguished, as 

 the urediniospores are always echinulate or verrucose with 

 several g'crm-pores, while the teliospores are usually smooth 

 (sometimes verrucose) with only one apical germ-pore. The 

 wall of the teliospore is, also, usually thicker. 



Arthur divides this genus chiefly into four as follows : 



Life cycle with all the spore forms Nigredo. 



Life cycle with pycnia, aecia and telia .... Uromycopsis. 



Life cycle with pycnia, uredinia and telia . Klebahnia. 



Life cycle with pycnia and telia Telospora. 



The genus is a very large one embracing over 500 species. 



Uromyces Scirpi Burr. 



Nigredo Scirpi (Cast.^ Arth. 



0. Pycnia amphigenous, numerous, scattered, incon- 

 spicuous. 



1. Aecia amphigenous, gregarious, on discoloured spots, 

 short cylindrical ; peridium pale yellowish, the margin lacerate, 

 recurved. Aeciospores globoid or broadly ellipsoid, 16-21 by 

 18-24/x; wall colourless, thin, minutely verrucose. 



II. Uredinia amphigenous, elongate, remaining covered 

 for some time by the epidermis. Urediniospores mostly 

 ellipsoid, 16-23 by 22-40/a; wall light brown, sparingly 

 echinulate, pores 3 or 4, equatorial. 



III. Telia amphigenous, oblone; oi- linear, long covered 

 by epidermis, compact, brownish-black. Teliospores fusoid or 

 clavate ellipsoid, 17-22 by 33-46/i, rounded at the apex, some- 

 times conical; wall light brown, thickened at the apex to 8/i*; 

 pedicel firm, hyaline, or light brown, oqualliTig or longer than 

 the spore. 



