1903J Yukon Hepatic/E. 19 



apices, it is the postical lobe which is smaller and more 

 sharply pointed, just the opposite of what we find in Mesopty 

 chia Sahlber^ii. The leaf-cells of L. Ruiheana average 

 0.023 X 0.032 mm. at the margin of the leaf, 0.055 '^ 0.030 mm. 

 in the middle and 0.055 ^ o 039 mm. near the base. They are 

 therefore a little larger than in the Mesopiychia and are more 

 distinctly elongated in the median and basal portions of the leaf 

 The trigones of the two species are similar, but the vsrruculae 

 the cuticle of L. Rutheana are fusiform in shape, rather than 

 oval or circular, and lend the leaf-surface a distinctly striated 

 appearance. The underleaves of L. Rutheana are much more 

 variable than in Mesopiychia Sahlbergii. They are occasion- 

 ally bifid but are more commonly trifid to quinquefid with the 

 median division distmctly larger than the others. The divi- 

 sions are lanceolate and euvl in long filiform points which are 

 commonly curved in various ways In some cases one or 

 more of the divisions arise from the surface at the base of the 

 underleaf instead of from the margin. The divisions are 

 often sparingly ciliate. but each one rarely shows more than a 

 half dozen cilia and the latter are shorter and broader than in 

 the Mesopiychia. 



The perichaetial bracts of L. Ruiheana are broader than 

 long, measuring 2.5 x 3 mm., and commonly show obtuse 

 lobes. The perianth is very large, measuring when mature 

 5 mm. in length and 1.4 mm. in diameter; its wall is three to 

 five cells thick (o. 14 mm. ) at the base, two cells thick to about 

 the middle and one cell thick in the upper part. The perianth 

 is gradually narrowed above the middle but is not distinctly 

 beaked nor contracted at the mouth. The latter is minutely 

 setulose, the thick-walled setulae being two cells long or less. 

 With respect to the folds of the perianth descriptions vary. 

 Lindberg states that it is obtusely trigonous, the third keel 

 being postical, but asserts that while young it is often later- 

 ally compressed. Limpricht emphasizes the lateral com- 

 pression and adds that there is sometimes a shallow groove 

 down one lateral face and a corresponding low ridge down 

 the other, sometimes a groove on each face. He also states 

 that a trigonous perianth with the third keel antical is of occa- 



