Arthur : New species of Uredineae 33 



erect, erose ; aeciospores globoid, 18-22 f± in diameter ; wall thin, 

 1 fi thick, pale-yellow, minutely and closely verrucose. 



On Triostetim angustifolium L., Perry ville, Missouri, May, 

 1884, C. H. D erne trio. 



No aecial or other form of rust is recorded on this host, or any 

 closely related one. It is probably a heteroecismal species. 



Aecidium Cardui sp. nov. 



0. Pycnia epiphyllous, in small groups, immersed, inconspicu- 

 ous, punctiform, subepidermal, globose, 130-180 fit in diameter. 



1. Aecia hypophyllous, crowded in circinating groups, 3-5 

 mm. across, on discolored spots ; peridia short, cylindrical, margin 

 erect, erose; aeciospores globoid, small, 15-18 by 16-20//; wall, 

 nearly colorless, very thin, 0.5-1 //, very minutely granulose. 



On Cardims Hookerianns (Nutt.) Heller (Cirsium Hookerianiun 

 Nutt.), Sandcoulee, Montana, July 28, 1887, F. W. Ander- 

 son 82. 



The common rust on various thistles, which extends across 

 the continent and is especially common westward, is Puccinia 

 Cirsii Lasch., and is a species having uredinia and telia, but no 

 aecia. P. suaveolens (Pers.) Rostr. is a similar species found only 

 on Cardims arvensis, while P. Cnici Mart., occurring on Carduns 

 lanceolatus, has aecia of a wholly different and peculiar sort. There 

 appears, therefore, to be no recognized species of rust on thistle to 

 which this Aecidium can be referred, and it is consequently de- 

 scribed as an independent form. Whether it belongs with an 

 autoecious or heteroecious species can not be stated. The col- 

 lector only included leaves of the host, and did not supply a specific 

 name. The material has been submitted to Dr. P. A. Rydberg, 

 of the New York Botanical Garden, who gives the above name, 

 but with some degree of uncertainty, due to the very scanty 

 material. 



Aecidium Argithamniae sp. nov. 



0. Pycnia epiphyllous, few in orbicular groups, not crowded, 

 punctiform, honey-yellow becoming dark-brown, conspicuous, 

 immersed, in section globoid, large, 150-175// across. 



1. Aecia hypophyllous, on discolored spots in orbicular or an- 

 nular groups, 2-5 mm. across, not crowded, cylindrical, short, 

 margin erect, erose or lacerate; aeciospores globoid, 15-18 by 



