Descriptions of American Uredine.-e, II. 



By J. C. ARTHUR and E. W. D. IIOLWAY 



The second fascicle of Uredixe.e Exsiccate et Icones, 

 upon which the following descriptions and comments are based, 

 includes only grass forms, i. c. species whose uredospores and 

 teleutospores occur upon the Graminete as host plants. The 

 first fascicle of this series, containing Lepto-uredinecR^ was 

 issued September, 1S94. and the descriptions of species in- 

 cluded were subsequently pubhshed in this journal (3:44-57 . 



Every collection in the distribution is illustrated by drawings 

 of the spores, these being numbered upon the plates to corre- 

 spond with the number of the packet. Arabic numbers are 

 used to designate the species, and letters to designate the sev- 

 eral collections under each species. The plates are issued both 

 with the Exsiccat.e and the Descriptions. 



The drawings have in all cases been made directly from the 

 material of the distribution, and are drawn to a uniform scale. 

 The forms of spores chosen for illustration are those most com- 

 monly seen under ihe microscope, with an occasional deviation 

 to show one-celled forms among species of Pucciuia, and to 

 show uredospores found in teleutosori gathered late in the 

 season. The attempt has been made to represent the form of 

 the spores, thickness of walls, and other details, as faithfully as 

 possible, but this could not be carried out as fully as desired in 

 the case of the sculpturings upon the surface of the spores, as 

 they are in all instances too minute to be accurately drawn upon 

 the scale adopted. It has also been impossible to fully indicate 

 the number and position of the germ-pores of the uredospores 

 in very many cases, especially when the spores were those found 



377 



