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The Lejeuneae of the United States and Canada 
By ALEXANDER W. Evans 
(PLATES 16-22) 
The subtribe Lejeuneae, as defined by Schiffner, is made up of 
the large and comprehensive genus Lejeunea as understood by | 
Spruce. The latter author divided this genus into thirty-seven 
natural divisions, which he looked upon as subgenera, while Schiff- 
ner raised nearly all of these subgenera to generic rank. Each of 
these authors has his own adherents. Writers on the hepaticae 
of Europe, where the Lejeuneae are poorly represented, tend to 
follow Spruce, recognizing but a single genus, while writers on the 
hepaticae of tropical regions, where the Lejeuneae attain a most 
luxuriant and varied development, tend to follow Schiffner. It is 
probable that an intermediate course would be more nearly cor- 
rect, that some of Schiffner's genera are worthy of generic rank, 
but that others ought to be united. Until, however, the many 
species are more clearly defined and more accurately understood 
than they are at present, it seems most practicable, and perhaps 
wisest, to recognize Schiffner's genera as such, at least in a tenta- 
_ tive way—a course which is adopted in the present paper 
For descriptions of the various genera, the reader is referred to 
the writings of Spruce * and of Schiffner.* Reference may also be 
made to a recent paper by the writer,f where the division of the 
group into genera is more fully discussed. 
HISTORICAL 
The earliest work devoted to North American hepaticae is 
that of Schweinitz, published in 1821. In this páper the genus 
Jungermannia i is still used in its old sense and includes seg ee 
* Hep. Amaz. et And. 63-308. 1884. 
T Engler & Prantl, Nat. Pflanzenfam 117-131. 1893. 
j The Hawaiian Hepaticae of the hie thie Trans. Conn. Acad. 10: 
387-462. . 1900. 
Me 
| ey Botanical Club, Volume VIII. 
[No. 2 issued 15 February, 1902.] 
113 
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