82 BRITISH HEPATIC^, 



Tufts of a dark olive or oliye-brown colour, loosely esespitose, 

 generally found growing on calcareous rocks, and often scattered 

 among mosses. 



Mhizomatous shoots creeping, leafless, brittle, dark brown. 



Stems ascending, rigid,, somewbat flexuose, simple or irregularly 

 innovant-ramose, ramuli patent or divergent. 



Rootlets capillary, white, pellucid, scanty on the foUose stems, 

 but more frequent on the stolons. 



Shoots gracile (f. 26, 2), of nearly equal diameter throughout 

 (iV to T^")j ^^"i from an inch to two inches in length, complanate 

 except at the apex, where the leaves are deflexed, in some speci- 

 mens sub-secund, having a peculiarly neat appearance from the 

 pectinate-pinnate leaves, which are scarcely altered when dry. 



Leaves (f. 26, 2) of nearly uniform size {-io"), the upper ones 

 closely imbricated, erecto-patent, the lower ones more distant, 

 alternate, patent-divergent, amplexicaul, divided for about a third 

 of their length into two conduplicate lobes, which are nearly equal 

 (f. 26, 5). 



Lower lobe roundish-ovate to ovate-oblong ; base somewhat 

 contracted, decurrent and reflexed ; apex abruptly pointed or api- 

 culate ; surface slightly convex, but not decurved (as in the last 

 species) except in the apical leaves ; margin irregularly denticulate, 

 the terminal teeth largest. In ^ the margin is nearly plane. 



Lobule obliquely ovate or ovate sub-quadrate, shortly pointed, 

 the outer margin frequently at right angles with the base so as to 

 appear truncate ; base rounded and decurrent, crossing the stem, 

 which is thus hidden ; surface concave, erecto-patent or reflexed ; 

 margin obscurely denticulate. 



The plica, which extends to a third or fourth of the length of 

 the leaf, is arcuate, and reflexed at the sinus, so that the lobes 

 project a little below it, and the leaves appear sub-falcate. 



Texture firm, chartaceous, little altered when dry, dull from 

 the presence of papillae. 



Colour a sub-opaque olive or olive-brown, in specimens from 

 exposed rocks nearly black. 



Areolation guttate, coarctate, the marginal cells very minute, 

 roundish, but increasing in size towards the centre of the leaf. 

 Cells polygonal, with a double outline, those of the margin sub- 

 quadrate, ttVo' to TTTo" in diam. Basal cells hexagonal, two " to 

 Too" by T^oo"' Trigones inconspicuous. 



Epidermic layer verrucose, the papillse broad and flat, and 

 resembling (as stated by Lindberg) groups of Cocconeis on the 

 frond of some water-weed. 



Inflorescence dioicous. 



Fertile shoots (f. 26, 1) somewhat stouter, and of a paler green 

 colour, probably from a more sheltered habitat, but not differing 

 otherwise from the barren stems. 



