PELTIGERA. 



169 



4. Peltigera polydactyla (ttoXvs, many, and Sa/cruXo?, 

 a finger) differs from P. canina chiefly in the smooth, shi- 

 ning character of the upper surface of the thallus ; fertile 

 lobules often very numerous, and somewhat digitately ar- 

 ranged. A variety, scutata (E. B. 1834), is marked by 

 shortened fertile lobules, and small orbicular apothecia. 

 Its habitat resembles that of P. canina, but it is much 

 more rare; it occurs in various Highland districts, as the 

 vicinity of Callander, from which we have seen specimens in 

 fine fructification. The variety scutata is chiefly found on 

 trees, and occurs in the Breadalbane Highlands, the neigh- 

 bourhood of Inverary, and other parts of Scotland, though 

 very sparingly. This species is more widely distributed in 

 central and northern Europe and America than P. canina 

 or P. venosa ; it occurs in the Antarctic regions, and in va- 

 rious warm climates, as the West Indies, Colombia, and the 

 Cape. 



5. Peltigera horizontals resembles the two preceding 

 species, differing chiefly in the apothecia being transversely 

 oblong, flat, and horizontal, with a thin, subcrenulate 

 margin. 



It also grows on moist, shady rocks, and on mossy trunks 

 and roots of trees in subalpine and lowland regions, but is 



