204 



Mycologia 



Many southern and western species are but imperfectly under- 

 stood and lack of time has prevented a careful study of some of 

 the forms already fairly well known. It should not be inferred 

 that every species of Puccinia has a correlated form in Uroniyces. 

 Correlation does occur frequently however, and appears not to be 

 confined to any particular family or order of hosts, although it 

 seems to be most common on the grasses and sedges. The reasons 

 for these limitations appear: to lie in a solution of the conditions 

 surrounding the evolution of the rusts and their hosts, and any 

 knowledge concerning the evolution of host and parasite undoubt- 

 edly has a close bearing upon the solution of this phase of the 

 problem. 



Purdue University, 

 Lafayette, Indiana. 



Explanation of Plates LXX and LXXI 



The drawings were outlined with the camera lucida at a uniform scale, 

 the reproductions representing approximately 470 diameters. In all cases the 

 urediniospores are represented with the hilum, or attachment of pedicel, 

 below. The urediniospores are drawn to show thickness of wall, surface 

 markings and position and number of germ pores. The teliospores are drawn 

 to show thickness of wall and apex, and the average length of pedicel. 



Fig. I. Puccinia subnitens on Distichlis spicata. 



Fig. 2. Uromyces Peckianus on Distichlis spicata. 



Fig. 3. Puccinia Caricis-Asteris on Carex tribuloides. 



Fig. 4. Uromyces perigynius on Carex intumescens. 



Fig. 5. Puccinia Ellisiana on Andropogon furcatus. 



Fig. 6. Uromyces pedatatus on Andropogon virginicus. 



Fig. 7. Puccinia uniporula on Carex pubescens. 



Fig. 8. Uromyces uniporulus on Carex gracillima. 



Fig. 9. Puccinia Distichlidis on Spartina gracilis. 



Fig. 10. Uromyces acuminatus on Spartina gracilis. 



Fig. II. Puccinia Pammellii on Panicum virgatum. 



Fig. 12. Uroniyces graminicola on Panicum virgatum. 



