248 UNDERWOOD: AMERICAN FERNS 
exclusively American and two others are regarded as common to 
the tropics of both hemispheres, while the other eleven are exclu- 
sively Old-World species ranging from Japan and Hawaii to Tas- 
mania and South Africa. Strikingly in contrast with this treatment 
is the arrangement given by Sturm of the Brazilian species,* of 
which he describes twenty-five ; almost half of which (twelve) are 
reduced by Hooker and Baker under the single species, Gleichenia 
pubescens, with their characteristic lack of recognition of specific 
characters. Sturm’s treatment, although nearly a half century 
away from the present, is the only critical and reliable one the 
American species have ever received, but concerns the South 
American species only, The species extending into Mexico and 
the West Indies have never received special attention, but their 
treatment has usually been that of Synopsis Filicum, in which the 
species are massed under four names as follows : 
1. Gleichenia longissima Blume. (Type from Java! ) 
2. Gleichenia pubescens H. & B. (Type from Venezuela and 
never examined by the authors of Synopsis Filicum !) 
3. Gleichenia pectinata Presl, (Type from Caracas, Vene- 
zuela ; a common tropical American species. ) 
4. Gleichenia dichotoma Willd. (Type from Japan ! ) 
The four categories which these tangles typify were made to 
stand for four sections of the genus by Diels,t and some of them 
on account of differences in spore characters, have been thought 
worthy of higher rank.§ 
I. Of the four tangles mentioned above, the first was founded 
ona Javan plant, and represents a large group of species, two of 
* Flora Brasiliensis 1); 219-238, 
859. 
We have now no reason for believing that any species are common to the Old 
World and the New. 
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