140 



ASCOLICHENES. 



deeply into the substratum. It grows at the circumference and 

 sometimes dies away in the centre (Figs. 138, 139, 140). 



2. The FOLIACEOUS. This also lies flat upon the substratum, 

 but is not firmly attached to and has a definite outline. It grows 



FIG. 136. Portion of a hymenium : A a thin 

 stratum on which the asci (s) are situated. 



FIG. 137. Spores of, a Cladonia, Lecanora and Pertusaria ; l> Bceomyccs c Sphinctrina; 

 d, e, f various species of Parmelia ; g, h Verrucaria in its younger and older condition ; i, 

 fe species of Leptogium. 



at the margin, and raises itself a little by free outgrowths and 

 lobes (Fig. 141). The rhizoid-strands spring out from its whitish 

 under surface (Fig. 131, r). 



3. The FRUTICOSE, which is attached to its substi-atum at a 

 small point from which it projects freely, either erect or pen- 

 dulous. It is more or less tufted, in the form of a bush (Figs. 142, 



FIG. 138. Lecanora sitb/i(sca : 

 a the bark on which it is situ- 

 ated; I the thai I us ; s the 

 ascocarp ; s' an ascocarp. 



Fis. 139. Graphis 

 (two species). 



FIG. 140. Pertusaria com- 

 munis. 



143). These three thallus-forms gradually pass over by many 

 intermediate forms into one another. 



The Lichens, like other Ascornycetes, have very variously 



