NEW BRITISH HEPATICLE. 87 



of the same colour, obscured in some parts by the fibrillar which 

 proceed from it, and which, as in all of the Marchantiece (for, as 

 pointed out by Hoffmeister, Ricciais only an angiocarpous section of 



thai tribe] — are of two kinds : simple, translucent, capillary rootlets, 

 and others, which seem dotted, from the presence of peculiar clavate 

 thickenings within the tubules (f. 17) ; sometimes the rootlets are 

 varicose, or bulbous at the apex. 



On section the frond is seen to be nearly trigonous (f. 17), tex- 

 ture solid and fleshy, destitute of lacuna', central stratum chloro- 

 phyllose, superficial cells arranged in linear series, conical at the 

 apex. 



J'istiUidea scattered along the carinate base of the lobes, young 

 fruit immersed, at length elevating the epidermis until it ruptures, 

 and allows the escape of the spores. 



Spores smaller than in R. bifurca, but not so much so as in the 

 figures (8 and 18), the former of which is magnified to twice the 

 diameter, so as to show the surface markings. Colour, dark-brown, 

 cremate reticulate. 



A short notice of R. sorocarpa appeared in the March number 

 of " Grevillea," by Dr. Braithwaite, so that I should not have 

 recurred to the subject (although I had made drawings at the time 

 with the intention of describing the species), but for the discovery 

 of a nearly allied form, and the difficulty of discriminating such 

 minute species from descriptions only. I trust, therefore, the 

 figures given will facilitate the study of these interesting additions 

 to our Flora, and perhaps lead to the recognition of cognate species. 



When the new Riccia was first sent to me by Mr. Watkins, I 

 referred it doubtfully to R. sorocarpa, for, possessing only Linden- 

 berg's monograph, I was misled by the figure and description of 

 his R. minima (under which R. sorocarpa, Bisch., is quoted as a 

 Bynonym), but in which the lobes are acute, and purple on the under 

 side. This form, although published in Syn. Hepat., p. G01, as a 

 distinct species, appears to me to come very near R. bifurca, of 

 which it may prove only a small variety. 



The smaller forms of R. glauca may be distinguished by their 

 much thinner texture, and the absence of the characteristic invo- 

 lution of the margins. 



Lastly, from R. nigrella, which it approaches in size, and the 

 linear involute lobes, it may be known by the absence of the row of 

 roundish, purple scales with which that species is clothed externally, 

 and which are met with in no other European Riccia. 



Probably A*, sorocarpa may be found in other localities ; but, 

 except after rain, it is very difficult to make it out, the particles ol 

 earth adhering to the marginal rootlets of the inflexed fronds, im- 

 parting to it nearly the same colour as the surface on which it grows. 



PI. 18, fig. 10, R. sorocarpa, natural size ; 11, 13, 14, 15, fronds 

 expanded X 16. 12, inferior aspect of frond. 16, appearance of 

 the segments when dry. 17, Transverse section, exposing sporan- 

 gium X 60. 18, spores X 120 diam. 



