NortH AMERICAN SPECIES OF LESKEA 479 
On rocks, rotton wood and bases of trees. (In Europe com- 
monly found on roofs, slate, tile or wood.) 
TYPE LOCALITY: Germany. 
DistRiBuTION : From Lake Superior (Wolle, Macoun) west- 
ward to British Columbia (Macoun) and northward to the Yukon 
(Williams); Colorado (Blake & Holzinger); Minnesota (Holz- 
inger). 
ILLusTRATION : Husnot, Musc. Gal. pl. 86. 
Widely distributed and quite variable, Z. tectorum is usually 
easily recognized when once understood. Its leaf-cells, broad, 
plump, rounded, glassy, furnish its most distinctive character. Its 
leaves are quite like those of Amélystegium adnatum but somewhat 
smaller. This differs, however, in having its leaf-cells longer and 
Narrower, especially in the upper part of the leaves, so that no 
difficulty need be experienced in discriminating between the two 
species. The closely allied European Leskea catenulata (Schwagr.) 
Brid., undoubted specimens of which have not as yet been re- 
ported from North America, may be known by its narrower, 
longer and thicker costa, usually reaching the middle and not 
forking, and by its thick-walled leaf-cells. 
The type of Z. Wollei Aust. has been compared with European 
specimens of L. zectorum, with the result of finding them nearly or 
quite identical. While the median leaf-cells are slightly longer, 
sometimes more rhomboidal than in the ordinary forms of this 
species, the same variations occur in foreign specimens. The 
cotype of Pseudoleskea malacoclada C. M. & K., through the kind- 
nese of Prof. Macoun, has likewise been seen and carefully exam- 
ined. Although it is slightly stouter and the basal margins of 
the leaves are more commonly recurved, it differs in none of the 
essentials from the specific type of L. ¢ectorum. 
14. Leskea tectorum flagellifera var. nov. 
In somewhat dense compact tufts, pale green to yellowish- 
brown ; stems prostrate, pinnately branched ; branches filiform 
with numerous flagellate deciduous branchlets; stems defoliate, 
rarely with rudimentary leaves ; branch-leaves as in type but usually 
much smaller; leaf-cells smooth, clear, oval-rhombic ; leaves of 
branchlets very small, 0.05—0.1 mm, wide, 0.I-0.2 mm. long. 
Differs from L. Williamsi filamentosa by its entire leaves and 
larger leaf-cells. Type of variety collected by Mr. R. S. Williams 
