BRITISH HEPATICiE. 23 



their own half-diameter, vertically patent, or erecto-patent when 

 moist, erect when dry, but otherwise unaltered, very concave, round 

 or elliptic-obovate, the base contracted and clasping the stem, from 

 ¥" to \"' long ; sinus deep, angular, equal to a third of the length ; 

 lobes equal, acutely cuspidate ; margin with a uniform narrow revo- 

 lute border, so that it appears thickened. Near the base of the 

 shoots, and on the innovations, the leaves are scarcely broader than 

 the diameter of the stem, but on the main shoots they gradually 

 increase in size towards the apex. 



The texture is firm and dense, Isevigate. Colour deep black, by 

 transmitted light a warm brown. Cells minute, dotted, the walls 

 thick. Marginal cells subquadrate, xtVo" 6ach way ; near the centre 

 they are about xi\^" by yr^"; basal cells y^" by ttVo"- 



Dioicous. Pructiflcation ? 



Dr. Lindherg, whose eye notliing seems to escape, states " that at the base, of the 

 leaves of N. revoluta from Dovrefjeld, he has observed that the cells in the mid-line are 

 arranged in two layers," the only instance of an approach to a nerve, as in Mosses, 

 known among the Foliose Hepaticse. In Diplophyllum alhica/ns, what appears to be a 

 nerve is merely a series of more elongated cells, and we observe a similar enlargement 

 of the basal cells in Frullania and other species. To Dr. Liiidberg we owe the iden- 

 tification of this rare species, which, with his accustomed liberality, he at once com- 

 municated to me ; thus enabling me to publish another species of Nardia new to our 

 Mora. N. revoluta was collected by Mr. David Orr so far back as 1851, but mis- 

 taken for Andrcea alpina, which it resembles in habit and colour. Only barren speci- 

 mens have been met with. 



Himalayan specimens, collected by Dr. Hooker, differ only in their greater 

 luxuriance, in the leaves being sub-secuud, and the shoots recurved at the apex. In 

 some respects it is intermediate between N. ema/rginata and N. Funckii, but it cannot 

 well be confounded by any one who attends to the diagnosis. No other species, with 

 which I am acquainted, has the margin of the leaf uniformly revolute. 



The leaves of N. emarginata are reflexed at the base only, but the lobes are 

 always plane ; gind in N. picea, which resembles it most closely in size and colour, 

 the margin is somewhat incurved. The leaves of If. densi/olia are more crowded, 

 the segments shorter and less acute, and the external borders only are recurved, not 

 the lobes. 



I hope to supply a figure of If. revoluta before the completion of this work, mean- 

 while I would refer to Grevillea, pi. 13, f. 19 — 25, where the enlarged shoot (f. 20) is 

 very correctly lithographed. 



^. MesopJiylla, Dumort. 



6. Nardia scalaris, G. Sr B. 



Dioicous. Shoots creeping or erect, radiculose, slightly com- 

 pressed ; leaves sub-vertical, arcuately imbricated, orbiculate, con- 

 cave, upper ones retuse ; amphigastria broadly subulate ; involucre 

 compressed, obovate, urceolate ; capsule oval. 



