Explanation of Plates. 



The drawings have been made from a Zeiss microscope bearing a D 

 objective and No. 8 compensating ocular, and by the use of an Abbe camera 

 lucida. They are uniformly drawn to a magnification of 625 diameters, and 

 reduced in engraving to 470 diameters. The essentially correct dimensions 

 of the spores may be obtained from the plates by multiplying the measure- 

 ments taken in millimeters by two, the results being in mucros (//). 



The pores shown for the uredospores do n >!; always represent the full 

 number, but only those that were evident. When the scar on the uredo- 

 spores left b,' the fall of the pedicel is shown, it is placed lowermost. 



Explanation of Plate IV. 



i8<r. Uromyces alopcc-tri Seym. — Six teleutospores. 

 i8£. " " " — Sis uredospores. 



19?. '• grammicola Burr. — Seven teleu'ospores 



xqb. " " " — Seven teleutospores and three uredo- 



spores. 

 ior. •• " " —One te'eutospoie and four uredospores. 



20a. Pitccinin pauici Diet. — Sevm teleutospores and three uredospores. 

 20b. " " " — Seven teleutospores and three uredospores. 



20c. " " . " — One teleutospore and four uredospores. 



