Occasional Notes. 313 
Having recognised this peculiar character it enables 
us to go a step further in understanding and justly esti- 
mating the modification of other characters which the 
plants possessing it exhibit. Pteridologists are divided 
in opinion as to whether the differences which herba- 
rium specimens show are the natural variations to be 
expected from a widely diffused type, or whether they 
represent distinct species. To form a satisfactory opi- 
nion on this point one must be in a position to be 
able to examine wild plants ; for, as they are so 
large, herbaria specimens are too fragmentary and 
otherwise, as I have indicated in regard to the cov- 
ering of the sori, imperfect to afford reliable guidance ; 
but the physical conditions of this colony are such 
that the plants abound everywhere on the coast lands, 
and afford under the best circumstances opportu- 
nity for this careful examination. There are two very 
distinct types in Guiana, which differ from each other in 
such marked features as to attract notice at a distance. 
The extent of the variation in each is slight here and 
strictly within the lines of its separate individuality, 
neither partaking of the distinguishing charadteristics 
of the other. These two plants are as distinct as any 
two closely allied species I know in any genus, and 
this experience has led me to the conclusion that the 
members of Chrysodium which are scattered over the 
world in tropical and warm temperate countries may not 
be, as is so often regarded, merely variations of one 
species. From my own examination of specimens and 
figures I am convinced however, that most of them do 
belong to a single variable specific type, and that type is 
the commoner of the two local states. 
PP 
