7i REVUE BRYOLOGIOUE 



dry, darker below and interwoven with brownish strongly 

 papillose rhizoids. Stems elongate, erect, filiform, stiff, 

 brittle, ramidose, in section obscurely 5-anglcd, with a cen- 

 tral strand of a few small thin-walled cells becoming ob- 

 solete above, three to four rows of large thin-Walled cells 

 forming the ground tissue and a marked cortical layer of 

 one to two rows of small incrassatc cells, yellowish in the 

 younger and or^inge in the older parts of the stem. Leaves 

 small, 0,55 to 0,80 mm. long and 0,36 to 0,40 mm. broad, 

 ovate-lanceolate, shortly acuminate, concave,narrowly decur- 

 rent, imbricated, not twisted when dry, erecto-patent when 

 moist ; margin plane without a distinct border, and entire 

 or subdenliculatc near the apex. Nerve strong, yellowish 

 throughout, percurreut or generally very shortly excurrcnt, 

 thickened below where it is 50 to 70 ^ broad, gradually 

 tapering above, in section showing one or two ventral layers 

 of two or three large cells, six to eight medium sized dorsal 

 cells, and eight to ten small slereid central cells. Leaf cells 

 somewhat incrassate, shortly rhomboid above, 25 to HO '^ 

 long and 12 to 15 p. broad, more elongate below, 30 to 50 ^ 

 long and 12 to 20 ^ broad,, and rpiadrate, to 20 pt broad, at 

 the basal angles, where they are usually yellowish, beco- 

 ming orange with age, the marginal cells narrow, sub1i- 

 near, but not forming a distinct border, 10 to 42 ja long and 

 8 to 10 ti broad, terminating shortly below the apex 

 and between which point and the apex the margin is often 

 obscurely denticulate. 



Ilab : On the face of rocks in the bed of a stream Allt 

 , Sugach, Ben Narnain, Argyllshire, Scotland, in company 

 with B. Mlldeanum^ B. fUi former llhacomiirhun ellipti- 



cum\ etc., 22 ^^> July 1898, II. N. Dixon, 



B. claviger Kaur. (wliich M*" Limpricht refer to B. vero- 

 ncme Do Not.) is found in similar localities and might pos- 

 sibly be mistaken for it in the field. The stems, however, 

 are paler and distinctly catcnulate , while the rounder 

 leaves, with short Ihin-walled cells and weaker nerve 

 abundantly distinguish it under the microscope. The almost 

 smooth rhizoids and the hardly differonciate cortical cells 

 of iJ. clavirjrr also form important dislinclive characters. 



By llie distinct cortical layers of the stem, B. Dlxorri 

 resembles the species of the sect. Auumohrijum^ but the 

 latter have a much more dense areolation, formed of nar- 

 rowly linear crlls. 



The axils of the upi)er leaves of some of the stems or 



B. Dixoni bear small buds wilh short somewhat modified 

 leaves, which appear to be ill-defined and, as it were, rudi- 

 mentary gemmae, somewhat similar to those wliich are 

 occasionally found on B, argcnteinn L. (Vide Correns, Un- 



