120 LEJEUNEAE OF THE UNITED STATES AND CANADA 
Americana and Cololejeunea Jooriana have been found as far north 
as North Carolina, and Microlejeunea lucens apparently occurs in 
Virginia. Six of these southern species have not been collected - 
outside of Florida. With the exception of Cololejeunea Macounit, 
of British Columbia, no species are known from the Pacific Coast 
region ; no species moreover have been reported from the Rocky 
Mountains nor from the Great Plains east of the Rocky Mountains, 
their absence or scarcity apparently being due to the dry atmo- 
spheric conditions. With regard to the number of species in indi- 
vidual States, Florida leads with fifteen, Louisiana ranks second 
with nine and Alabama third with eight. Few of the remaining 
States have more than three species apiece, and even east of the 
Mississippi River there are several States which have had no Le- 
jeuneae whatever reported from them. 
The brief notes which have just been given are mainly of tem- | 
porary value. The Lejeuneae have been so largely neglected by 
collectors that our knowledge of their geographical distribution is 
at best very incomplete. The rich harvest of species which 
Underwood gathered in Florida shows how little we had previ- 
ously known about the Lejeuneae of that state and indicates that 
much is still to be learned. The collections of Langlois in Louisi- 
ana and of Mohr in Alabama point to similar conclusions. Even 
in the north, the recent discovery of Lejeunea patens in Newfound- 
land and in Cape Breton shows how fragmentary our knowledge 
really is, It should be noted also that specimens exist in herba- 
ria, too incomplete for identification and yet undo ubtedly distinct 
from any recorded species. Some of these are probably identical 
with described species from tropical America, others are probably 
undescribed ; but for the present they must be left in doubt. It 
is clear, therefore, that much remains to be done to complete our 
knowledge of the Lejeuneae, and it is to be hoped that the pres- 
ent paper may incite collectors to pay more attention to these in- 
conspicuous but beautiful plants. 
The revision which follows is based largely on the collections 
of Lejeuneae in the Underwood herbarium, in the United States 
National Herbarium and in the herbaria at Yale University. The 
curators of other herbaria have also been most generous in allow- 
