LICHItfEI. 129 



ble difficulties in the way of continuing to regard it as ordinarily 

 distinct from them, reference may be made to the author's Gen- 

 era Lichenum, p. 56-64, etc. 



The spore-history of the Cottemei offers an evident contrast 

 to that of the Pannariei, in that while in the latter the greater 

 proportion of the forms, and all the more typical ones, have 

 simple spores, the higher features shewing themselves only in 

 the receding sections, the confused and at length aberrant struct- 

 ure of which assimilates them to Eucollemel, it is the bulk and 

 most typical portion of the former which displays the higher 

 spore-characterization, and only in general the reduced and re- 

 ceding clusters 'in which the spores are simple. We descend 

 thus from the foliaceous Pannariae to the sections Lecothecium 

 and Janella ; as we ascend from Pyrenopsis and Omphalaria to 

 Leptogium and Hydrothyria. But in both alike the ultimate con- 

 dition of tne spore is that of the Coloured Series ; and those 

 spores therefore the structure of which represents earlier stages 

 of spore-development, however without colour and apparently 

 equivocal, are to be taken for decolorate members of the same 

 Series. 



Sub-Fam. 1. LICHINEI. 



Thallus filamentous or shrub-like j the gonimia either 

 constituting an axis (as in Sirosiphon, and other types of 

 Algce, with which Class the principal members of the present 

 Sub-Family were formerly placed, as Sirosiphon is now, by 

 some, with Lichenes) but interpenetrated and surrounded 

 by filamentous elements (hyphse), and crowded at length by 

 the development of the latter into a regular gonimous layer 

 (Sect. 1), or concatenate (Sect. 2). Medullary layer more or 

 less parenchymatous. Apothecia globose ; oftener biatorine. 



Sect. 1. Ephebei. Thallus filamentous, sirosiphonoid. 



The plants to be now described are distinguished from Alga, as 

 well by the possession of apothecia, as of hyphae. In other re- 

 spects, however, the present section is so close to certain Algal 

 types (especially Sirosiplion, Kiitz.), and this resemblance ap- 

 peared otherwise of such difficult explanation, that the question of 

 parasitism long since suggested itself. Ephebe pubescens, in its 

 9 



