Explanation of Plates. 



The drawings have been made from a Zeiss microscope fitted with 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 measurements taken in milimeters by two, 

 the result being in microns (//). 



The pores shown for the uredospores do not always represent the full 

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

 spores left by the separation of the pedicel is shown, it is placed lowermost. 



Explanation of Plate I. 



45a. Uromyces aristid.e E. & E. 



On Aristida basiramea Engelm., from Nebraska. 

 Two uredospores and five teleutospores. 



456. Uromyces aristid.e E. & E. 



On Aristida oligantha Michx., from Texas. 

 Five teleutospores. 



46a. PUCCINIA ARISTIDICOEA Hertfl. 



On Aristida fasciculata Torr., from Mexico. 

 Three uredospores and five teleutospores. 



466. PUCCINIA ARISTIDICOLA Hetltl. 



On Aristida fasciculata Torr., from Mexico. 



Four uredospores, one drawn as if opaque, and four teleutospores. 



47a. Uromyces epicampus Diet. & Holw. 



On Epicampus macroura Benth., from Mexico. 

 Three uredospores and six teleutospores. 



483. Uromyces minimus Davis. 



On Muhlenbergia sylvatica Torr., from Wisconsin. 

 Four uredospores and five teleutospores. 



