412 INTRODUCTION TO CETPTOGAMIC BOTANY. 



448. The first sub-tribe consists of the Lichens to which 

 Montagne has given the name of Peltigeri, from their target- 

 like discs, which are either orbicular or reniform, and at first 

 concealed by a veil, the fragments of which often remain at- 

 tached to the margin. They are frequently terrestrial species, 

 and present beautiful expanded fronds. The true Peltigeri are 

 remarkable for the venose appearance of the under surface, 

 which is attached to the ground by numerous white or pale 

 strigose hairs. The fruit is marginal and sometimes elongated, 

 so as to give the frond a digitate aspect. The species are 

 closely allied, and are well known to most observers of natural 

 objects, from the pretty manner in which they adorn ex- 

 posed hillocks, or the tops of earthen walls. They are often 

 studded with a little red fungus, which adds greatly to their 

 beauty. 



449. Nephroma is distinguished by its reniform, marginal, 

 hypophyllous discs, and frequently grows on the trunks of trees 

 in shady woods, while Solorina has the fruit scattered over the 

 frond, and often forms deep depressions. The under side of one 

 species is of the most beautiful yellow, and is highly striking. 

 In Solorina saccata the fruit is at first superficial ; but a num- 

 ber of fibres are formed on the under side, penetrating the soU 

 and drawing down the disc beneath the general surface. In 

 Solorina crocea there are veins on the under surface, as in 

 Peltigera venosa, but no fibres ; and as no rootlets are sent 

 out from the base of the disc, they remain superficial. The 

 genera, are, however, closely allied to each other, and are com- 

 prehended in one by Fries and Endlicher. 



450. The sporidia of Solorina saccata are uniseptate and 

 granulated, resembling some Puccinia ; the growth of Pel- 

 tigera polydactyla, from the mycelium, is beautifully traced 

 through every stage of growth by Tulasne. Little excrescences 

 are first formed on the threads which, on the division of their 

 endochrome, at length give rise to distinct fronds. The sper- 

 matia of Peltigera canina and polydactyla are obovate and 

 obtuse, and might as reasonably be called stylospores as those 

 oi Abrothallus. In Ne]3hroma they are narrower and oblong. 



451. The genera are rare within the tropics, but Peltidea 



