85 



NEW BRITISH HEPATIC^. 



By Dr. Carrington. 



Riccia bifurca. Iloffm. 



Fronds tumid, flabellate ; lobes elliptic-obvate, cuspidate, retuse, 

 or bifurcate ; margin elevated, rounded ; disc nearly plane, glaucous- 

 green ; lower surface sphacelate. 



Iloffm. PL Cryp. Germ. p. 95 {excel, syn. Michelii). Lindenberg's 

 Riccice, p. 65, t. 20, f. 1. N. ab. E. Hep. Eur., iv., p. 396. Syn. 

 Hcpat. p. 600. 



Hab. On limestone rocks by the shore, Barmouth, Oct. 18G7 ! 

 Aberffraw, W. Wilson, 1830 ! Levens Park, Westmoreland, on 

 limestone rocks, G. Stabler, Feb., 1870 ! Head of Glen Dole, 

 Forfar, J. Sadler, 1872 ! 



Patches 2 to 3 inches in diameter (pi. 18, f. 1), glaucous-green, 

 margin and underside purplish-black ; fronds crowded and fre- 

 quently imbricated, firmly attached to the surface, but from the 

 tumid margins appearing to stand boldly from it. Like all the Riccice, 

 the individual fronds increase by repeated bifurcations from the ter- 

 minal lobes, which diverge more or less, so as to assume a pedate, 

 or flabellate outline — not stellate, as usually described by authors. 

 In old tufts, the periphery is found to describe the section of a 

 circle, or series of circles, the centres of which, from the decay of 

 the older fronds, are incomplete, or occupied by newer fronds. 



Segments of the fronds, 3 to 6 lines in length, by a line in dia- 

 meter, contracted at each end, elliptic-spathulate, rarely oblong, 

 cuspidate at the apex (f. 4, 5), or obovate-emarginate, and more 

 or less deeply furcate. Frequently the lobules are separated 

 from each other by a mere chink (f. 2, 3), but near the base 

 of the frond they are patent or divergent (f. 5). Their charac- 

 teristic feature, however, is the bold, tumid border, most con- 

 spicuous near the apex, but surrounding the lobes more or 

 less perfectly, and visible even in dry specimens. The depressed 

 portion is broad and plane, or slightly concave (f. 6), without any 

 defined mid-vein, as in R. sorocarpa. When in a state of fructi- 

 fication, the segments are sometimes contracted or deformed, but 

 generally retain the peculiar boat-like outline. On section the 

 border is found to be permanently thickened, not merely inflexed 

 (f. 7). Cellular tissue solid, homogeneous, upper stratum columnar, 

 intermediate portion darker-green, from the presence of numerous 

 gonidial cells. Epidermis of the lower aspect purplish-brown, 

 continued uniformly, or in irregular fascia over the margins. 



Rootlets numerous, either capillary and translucent, or papillose 

 within. Sporangia scattered irregularly over the disc of the frond, 

 at length rupturing the epidermis. Spores conspicuous, dark-brown, 

 three-angled, sub-cristate, rounded and reticulate-muricate on the 

 outer surface (f. 8, x. 120). 



The margin, in old fruit-bearing fronds, is sometimes irregularly 

 crenate externally, and the purple stratum disposed in spots or bars, 



