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 millimeters 

 by two, the results being in mucros (/n). 



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

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

 uredospores left by the separation of the pedicel is shown, it is placed 

 lowermost. 



Explanation of Plate I. 



35a. Puccinia tripsaci Diet. & Holw. 



On Tripsacum dactyloides TL,., from Mexico. 

 Five amphispores and four teleutospores. 

 36a. Puccinia polysora Unci. 



On Tripsacum dactyloides L>, from Mexico. 

 Four uredospores. 

 37a. Puccinia virgata Ell. & Everh. 



On Chrysopogon avenaceus (Michx. ) Benth., from Kansas. 



Four uredospores, three paraphyses and four teleutospores. 

 38a. Puccinia eluisiana Thuem. 



On Andropogon scoparius Michx., from Kansas. 



Three uredospores, one drawn as if opaque, and seven 

 teleutospores. 

 38b. Puccinia elusiana Thuem. 



On Andropogon scoparius Michx., from Iowa. 

 Two uredospores and eight teleutospores. 



