ARTHUR AND MAINS: GRASS RUSTS 413 
echinulate, the pores very indistinct, probably 2 and equatorial. 
III. Telia hypophyllous, scattered, squarish-oblong, 0.5—1 
mm. long, covered by the epidermis, compact with the spores 
adhering laterally, brownish-black due to discolored host-tissue; 
teliospores I-, 2- or 3-celled, short-cylindric, 8-14 by 24-39 un, 
rounded or depressed above and below, somewhat constricted at 
septa; wall pale-brown or colorless, smooth, thin, uniformly 1 u 
or less in thickness, but with an outer colorless layer swelling in 
in water to 2-3 uw above, demonstrable by staining; pedicel wanting 
or extremely short and colorless. 
On Olyra latifolia L., Mayagiiez, Porto Rico, January 30, 
1890, II, III, A. A. Heller 4443, communicated by P. L. Ricker; 
San German, Porto Rico, December 12, 1913, II, F. L. Stevens 
5849, 5855; Manati, Porto Rico, July 2, 1915, II, F. L. Stevens 
7700; Soledad, Cienfuegos, Cuba, November 7, 1915, ii, J. R. 
Johnston 247; Isle of Pines, Cuba, February 20, 1916, II, Britton, 
Britton & Wilson 14648; Ceballos, Cuba, March 24, 1916, II, 
J. R. Johnston 509; Guantanamo, Cuba, February 7, 1918, II, 
Ill, J. R. Johnston 1028 (TYPE). 

Fic. 1. Puccinia phakopsoroides: A, section showing part of a telial sorus and 
the adjoining host tissues; B, teliospores after treatment with potassic hydrate. 
X 625 diameters. 
There is a marked gradation evident in some tropical rusts, 
especially the grass rusts as indicated above, toward the produc- 
tion of thin-walled, pale or colorless spores. In the uredinia 
these spores are frequently accompanied with a fringe of incurved, 
hyphoid paraphyses. In the telia the spores are small and often 
compacted, long remaining covered by the epidermis. As usual 
in subepidermal forms, these teliospores have short pedicels. 
