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LEJEUNEA CAVIFOLIA 158 
Lejeunea patens is a paler plant than ۲۰ cavıfolia ; the lobes of 
its leaves spread more abruptly from the lobules and are more 
convex, especially when dry; the underleaves are more nearly 
orbicular and are smaller than the lobules, while the margins of 
both leaves and underleaves are distinctly crenulate from project- 
ing cells. The leaf-cells also, as a rule, are more strongly convex 
and show more conspicuous trigones and intermediate thickenings. 
Unfortunately the abrupt spreading of the lobe from the lobule is 
not always evident in Z. patens, especially on the leaves of the 
smaller branches. Neither is this character by itself to be wholly 
relied upon in separating the species, for in Z. 0 the lobe 
sometimes spreads widely also. The figures recently published 
by Pearson * show how variable both species are in this respect. 
It is only when the spreading lobe is found in connection with the 
other peculiarities of Z. patens that it becomes of value as a differ- 
ential character. 
Lindberg's variety planiuscula of L. cavıfolia, first distinguished 
simply as a form, hardly seems worthy of varietal rank. Ac- 
cording to the description, the plants of this variety are more 
elongated, less branched and broader than in the type, the leaves are 
less imbricated and less decurved, the lobules are relatively smaller 
and the cells have thinner walls and scarcely evident trigones. 
Faxon's specimens from Crawford Notch, New Hempshire, and 
Underwood's from Manlius, New York, agree with this descrip- 
tion and also with the specimens which Lindberg quotes, but they 
are connected with typical Z. cavifolia by intermediate conditions. 
Apparently their peculiarities are due to a moister habitat, which 
would naturally produce a laxer growth and lead toa diminution 
in the development of the lobules and of the cell-walls. 
Two specimens of Zejeunea distributed in Hepaticae Americanae 
should perhaps be noted here. One of them is the curious sub- 
merged ** Kantia aquatica” Underw., distributed as no. 107. As 
Underwood | himself has shown, this plant isa true Lejeunea, 
apparently related to L. cavifolia. Asa result of its submerged 
* Hep. Brit. Isles, ۸7۰ ro, zz. 1899. 
T Zejeunea serpylifolia, forma a planiuscula Lindb. Acta Soc. Sci. Fenn, 10: 
484. 1875. Lejeunea cavifolia, var. B planiuscula Lindb. Muse. Scand. 2. 1879. 
+ Bull. Torrey Club, 23: 383. 1896 (footnote). 
