t 



Rev. W. A. Lcigliton on the British Umbilicariae. 287 



pound : when it consists of a single leaf, this is sometimes 

 2 inches in diameter, of an irregularly orbicular outline, with a 

 few, rounded, shallow, crenate lobes, and nearly flat; in the 

 more common and complicated state, each leaf is seldom an inch 

 in diameter, usually much smaller, much and variously crumpled, 

 suborbicular, very uncertain in the number and shape of its 

 lobes, which are usually, however, few and shallow, their edges 

 waved and crenate : uj)per surface of a greenish copper-colour 

 when wet ; copper-brown, sometimes blackish, when dry ; very 

 smooth and even, excepting a few scattered minute black dots, 

 sometimes impressed, at other times slightly elevated : under sur- 

 face invariably quite black, clothed for the most part with innu- 

 merable entangled black fibres, which most frequently are pro- 

 truded beyond the edges,, so as to give them the appearance of 

 being fringed (which sometimes also they are in fact), less fre- 

 quently naked here and there, or nearly all over, and then 

 rough with minute shagreen-like granulations, and irregularly 

 reticulated (which is most remarkably the case towards the 

 centre), with elevated veins or threads, which are often detached, 

 except at their extremities, so as to form a coarse lacework : 

 substance coriaceous, but thin, flexible when wet, very rigid and 

 brittle when dry. Tricce rare, orbicular or elegantly lobed, flat, 

 appressed to the thallus, to which they are aflixed by the whole 

 under side, always destitute of a mar gin, and composed entirely 

 of numerous narrow gyri, which are much and variously subdi- 

 vided and contorted, but seem to spread from a common centre, 

 and frequently unfold, or grow out into elevated irregular clusters 

 of much-branched minute black fibres, and these clusters are of 

 more frequent occurrence than the tricse themselves." — Lich. 

 Brit, 



Our British plant coincides with specimens of U. polyrhizos 

 (Linn.) in my herbarium received from Fries fil., collected at 

 Upsal, Sweden. 



PLATEX.fig.il. 



In Mr. Borrer's herbarium are authentic specimens! from 

 xYcharius of G. hir^suta and G. vellea^ which appear to be iden- 

 tical. In the former the sporidia were not seen, but those of the 

 latter were double the size of those oi pellita (see PI. X. figs. ]2 

 and 13), consequently showing them to be distinct species. 

 Scha^rer's Exs. 137 ! and 138 ! were also identical with the 

 Acharian specimens. 



No British specimens have occurred to our notice ; though 

 Robson in his British Flora, p. 300, gives as a habitat for the 



* For the spermagonia see Tulasne, I. c. 



