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TWO HEPATICS NEW TO BRITAIN. 

 By W. E. Nicholson. 



During the autumn of 1912 I found in several stubble fields 

 in the neighbourhood of Lewes a small species of Biccia which 

 generally had some traces of violet colouring about it and was 

 most frequently ciliate. It bore some general resemblance to E. 

 Warnstorfii Limpr., but it seemed constantly different in the 

 more compact rosettes with shorter wider branches. This seemed 

 to point to R. commutata Jack, and on my submitting the plant 

 to Dr. Schiffner, he confirmed it as that species, remarking that 

 it was rather more compact than the plant from the original 

 locality and that from Dalmatia, but that this might well be 

 accounted for by the habitat, as morphologically and in the spores 

 it agreed well with these. B. commutata is no doubt closely 

 allied to B. Warnstorfii, and the differences may to some small 

 extent be accounted for by differences in the habitat of the two 

 species, B. Warnstorfii being perhaps more frequently found in 

 lighter soil than B. commutata ; but, on the other hand, the 

 differences are retained on the cultivation of both species in the 

 same soil. In Sussex the two species sometimes grow in the 

 same field, and Mr. H. H. Knight has found the same thing in 

 Gloucestershire. On the Continent B. Warnstorfii is credited 

 with a northern range, being principally recorded from Northern 

 Germany, while B. commutata has a distinctly southern dis- 

 tribution. Both plants will probably be found to have a much 

 wider distribution in Britain than is at present suspected. In 

 the autumn of 1912 B. commutata was much more abundant in 

 Sussex than B. glauca, with which it might perhaps be confused 

 in the younger stages, though if transverse sections be cut of 

 mature fronds of the two species there is no possibility of 

 mistaking one for the other. The following diagnosis, largely 

 borrowed from that of Dr. K. Miiller, may be of use in dis- 

 tinguishing the plant (K. M. Mus. Hep. 1 Abt. p. 191). 



Monoicous. Thallus small, dark vivid green, rarely reddish, 

 flat, two or three times forked, 2-7 mm. long and 1-1-5 mm. 

 broad. Branches linear, oval or ovate with margins here and 

 there stained with red, usually inserted almost rectangularly, 

 truncate to emarginate at the ends, with or without marginal 

 cilia and with a narrow channel only at the ends of the branches; 

 further back the upper side of the thallus is convex. Frond 

 section one and a half to three times as broad as thick, ellipsoid 

 in the older parts with rounded margins wider towards the apex, 

 slightly convex below, flat above with a short obtuse sinus and 

 bow-shaped towards the sides. Cells of the epidermis thin- 

 walled, spherical, without mamilla. Ventral scales colourless or 

 reddish violet, soon disappearing. Ostioles rising slightly above 

 the upper surface of the thallus. Spores brown 80-85 fx with a 

 distinct yellow and notched margin, closely papillose, areolte 

 consequently indistinct, 8 fj. wide, 6-8 visible in the diameter of 

 the spore. 



Journal of Botany. — Vol. 52. [April, 1914.] i 



