Arthur: Uredinales of Porto Rico 
235 
rectangular cells, augmented by a hypoclermal layer of very large, 
rectangular cells, the cells in both instances having unformly thin, 
but firm walls. The sori are situated below the hypodermal 
layer, often directly beneath a stoma. The resistance of the over- 
lying tissue evidently accounts for the angular and irregular 
spores of both uredinia and telia. 
The habitat for both Canna and Thalia is the same, and their 
manner of growth is similar. The two genera belong to closely 
related families, with many important characters in common. 
There are now many species of rusts known to go to more than 
one family of hosts. There seems no longer any good reason, 
either in the nature of the fungus or in the matter of convenience, 
for maintaining two specific names, and they are herewith united. 
48. PucciNiA MACROPODA Speg. An. Soc. Ci. Arg. 10 : 8. 1880. 
Uredo striolata Speg. An. Soc. Ci. Arg. 9: 173. 1880. 
On Am.vrantaceae : 
Ircsine elatior L. C. Rich., Desecheo, May 31, II, i6i^. 
The same rust in its characteristic uredinial stage was collected 
on the same host on the island of St. Thomas, May, 1906, by C. 
Raunkiaer, and on Iresine paniculata (L.) Kuntze in Cuba. 
March, 1903, by E. W. D. Holway. 
49. PucciNi.\ Rivinae (Berk. & Curt.) Speg. An. Mus. 
Buenos Aires 19 : 304. 1909. 
Aecidium Rivinae Berk. & Curt. Jour. Linn. Soc. 10 : 358. 1869. 
Endophyllum Rivinae Arth. N. Am. Flora 7: 126. 1907. 
Puccinia Raunkiaerii Ferd. & Winge, Bot. Tidsskr. 29 : 8. 1908. 
On Petiveriaceae (Phytol.\ccaceae) : 
Rivina humilis L., Desecheo, May 31, I, II, 1390. 
Collections on the same host have been seen from Cuba, June, 
1906, I, Mel. T. Cook, and from St. Thomas, Oct., 1906, I, II, 
III, C. Raunkiaer 1819, also on R. octandra L. from Cuba, April,’ 
1905, I, Baker & \^an Herman 4/73. 
