488 HEPATIC^. 



broad, and its remarkably firm texture ; it is also generally much 

 paler in colour, and is almost peculiar to limestone districts. 



Description of Plate CCXVIIL— Figs. 1 and 2. Plants 

 natural size. 3, 4. Ditto, slightly magnified. 5. Cross-section 

 of frond with young capsule x . 6. Ditto with capsule x 

 (Bischoff). 7-10. Cross-sections of fronds, when dry, x 31 

 (Cheddar, AVatkins). 11. Epidermis x. 12. Style x. 13. 

 Young spores x. 14. Spores x (Biscbofi'). 



4. Riccia bifurca, Jloff'm. 



Riccia hi/urea, Hoffmann, Deutschl. Fl. p. !):» (171)0) (excl. syn. Mich. tab. 57 

 fig. 4). 



Monoicous?, closely ctespitose, small; antical surface glaucous 

 green, margins and postical surface of fronds purphsh-black in 

 colour. Fronds crowded and frequently imbricated, firmly 

 attached to the surface, tumid-flabellate or pedate ; lobes elliptic, 

 contracted at each end or obovate, rarel}' oblong, cuspidate, retuse, 

 bifurcate or obovate-emarmnate, marmn elevated, rounded, antical 

 surface sphacelate ; texture solid, homogeneous, upper stratum 

 columnar, intermediate portion darker green, epidermis of the 

 postical surface purplish-brown. 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. 



Dimensions. — Fronds 375 mm. long x 2-5 mm. broad, 3" mm, 

 X 1"25 mm., 5" mm. x 2'5 mm,, from "3 mm. to "5 mm. thick 

 at the middle, near the margin '5 mm. to 7 mm. thick, spores 

 •095 mm., '1 mm. diam. 



Hab. — On ledges of rocks where there is a thin layer of soil 

 and mud-covered walls, chiefiy in limestone districts and near the 

 sea. Rare. 



1 . Penzance, JJ"^. Ciniiow. 7. Aberfii'aw, Anglesey, IF. IVihoUy 

 1830 ; Barmouth, Merionethshire, Br. Carrinyioii, 1887, on mud- 



