REPRODUCTIVE ORGANS 279 



as " hypophloeodal." But in some families, such as Roccellaceae, the thallus 

 attains a very advanced form and a very high production of acids. 



The conception of Graphidineae as a whole is puzzling, but one or other 

 characteristic has brought the various members within the series. It is in 

 this respect an epitome of the lichen class of which the different groups, 

 with all their various origins and affinities, yet form a distinct and well-defined 

 section of the vegetable kingdom. 



d. Cyclocarpineae. This is by far the largest series of lichens. The 

 genera are associated with algae belonging both to the Myxophyceae and 

 the Chlorophyceae, and from the many different combinations are produced 

 great variations in the form of the vegetative body. The fruit is an emergent, 

 round or roundish disc or open apothecium in all the members of the series 

 except Pertusariaceae, where it is partially immersed in thalline " warts." 

 In its most primitive form, described as "biatorine" or "lecideine," it may 

 be soft and waxy {Biatord) or hard and carbonaceous (Lecided), in the latter 

 the paraphyses being mostly coloured at the tips ; these are either simple or 

 but sparingly branched, so that the epithecium is a comparatively slight 

 structure. The outer sterile tissue forms a protective wall or "proper margin'' 

 which may be entirely pushed aside, but generally persists as a distinct rim 

 round the disc. 



A great advance within the series arose when the gonidial elements of 

 the thallus took part in fruit-formation. In that case not only is the 

 hymenium generally subtended by a layer of algae, but thalline tissue con- 

 taining algae grows up around the fruit, and forms a second wall or thalline 

 margin. This type of apothecium, termed " lecanorine," is thus intimately 

 associated with the assimilating tissue and food supply, and it gains in 

 capacity of ascus renewal and of long duration. This development from 

 non-marginate to marginate ascomata is necessarily an accompaniment of 

 symbiosis. 



There is no doubt that the Cyclocarpineae derive from some simple 

 form or forms of Discomycete in the Patellariaceae. The relationship 

 between that family and the lower Lecideae is very close. Rehm^ finds the 

 direct ancestors of Lecidea itself in the fungus genus, Patinella, in which the 

 apothecia are truly lecideine in character — open, flat and slightly margined, 

 the hypothecium nearly always dark-coloured and the paraphyses branched, 

 septate, clavate and coloured at the tips, forming a dark epithecium. More 

 definitely still he describes Patinella atroviridis, a new species he discovered, 

 as in all respects a Lecidea, but without gonidia. 



In the crustaceous Lecideaceae, a number of genera have been delimited 

 on spore characters — colourless or brown, and simple or variously septate. 

 In Patellariaceae as described by Rehm are included a number of fungus 



1 Rehm i8go. 



