108 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
The table indicates the presence in Cuba or in Porto Rico of 
only half as many species in each of the three genera, Coleosporium, 
Ravenelia, and Puccinia- Uromyces, or in all combined, as occur in 
Guatemala. The difference in abundance may be ascribed to the 
differences between insular and continental conditions, or to the 
diversity of topography, or to both factors combined. 
The only genera represented in Cuba, not found in the other 
West Indian islands, or the nearby continent, are Sphaerophrag- 
mium and Uromycladium, both based somewhat doubtfully upon 
material needing further field observations and study. The 
seemingly greater similarity to the rust flora of southern Florida 
and the regions bordering the Gulf of Mexico, than is shown by the 
rust flora of Porto Rico, has been previously pointed out,* as well 
as the surprisingly large number of short-cycle species. To go 
into a more detailed comparison of the Cuban rust flora with that 
of other regions is not likely to be particularly profitable at the 
present time owing to the imperfect data available, not only for 
Cuba, but even more so for most regions with which it might be 
compared. 
In the following enumeration twelve species are described as 
new, and five species are transferred to other genera, making new 
combinations. Most of the changes in genera are due to finding 
additional spore forms, but some are in the nature of quite new 
discoveries, as in the case of Uromyces cristatus, which was em- 
balmed under the name of Uredo, although not itself uredinial, 
or belonging to a species having a uredinial stage. 
The list introduces 15 species new to the North American flora, 
of which то species are exclusively Cuban, so far as present knowl- 
edge extends, the others being mostly South American forms. 
In conclusion it may be said that the present enumeration of 
140 species of Cuban rusts must be considered only the basis for a 
thoroughly scientific and economic exploration of the island for 
this group of obligate parasites. When sufficient taxonomic data 
are finally accumulated the still more interesting task of studying 
the species in relation to their distribution, the abundance from 
year to year, their origin on the island, and their relation to eco- 
nomic problems, can be taken up with interest and profit. The 
* Arthur, Rusts of the West Indies. Torreya 17: 24-27. 1017. 
