FAMILIES AND GENERA 307 



based on imperfect knowledge, it is not a little artificial ; also while magnify- 

 ing the significance of spermogonia and spermatia, he overlooked the much 

 more important characters of the ascospores. 



/. MtJLLER(-ARGAU). In preparing his lists of Genevan lichens (1862), 

 Miiller realized that Nylander's series was unnatural, and he found as he 

 studied more deeply that lichens must be ranged in parallel or convergent 

 but detached groups. He recognized three main groups : 



1. Eulichens, divided into Capitularieae, Discocarpeae and Verru- 



caroideae. 



2. Epicoriiaceae. 



3. Collemaceae. 



He suggested that, in relation to other plants, Eulichens approach 

 Pezizae, Hysteriaceae and Sphaeriaceae; Epiconiaceae have affinity with 

 Lycoperdaceae, while Collemaceae are allied to the algal family Nosto- 

 caceae. These three groups of Eulichens, he held, advanced on somewhat 

 parallel lines, but reached a very varied development, the Discocarpeae 

 attaining the highest stage of thalline form. Miiller accepted as characters 

 of generic importance the form and structure of the fruiting body, the 

 presence or absence of paraphyses, and the septation, colour, etc. of the spores. 

 A few years later (1867) the composite nature of the lichen thallus was 

 announced by Schwendener, and, after some time, was acknowledged by 

 most botanists to be in accordance with the facts of nature. Any system 

 of classification, therefore, that claims to be a natural one, must, while 

 following as far as possible the line of plant development, take into account 

 the double origin of lichens both from algae and fungi, the essential unity 

 and coherence of the class being however proved by the recurring similarity 

 between the thalline types of the different phyla. As Miiller had surmised: 

 "they are a series of parallel detached though convergent groups." 



g. REINKE. The arrangement of Ascolichens on these lines was first 

 seriously studied by Reinke 1 , and his conclusions, which are embodied 2 in 

 the Lichens of Schleswig-Holstein, have been largely accepted by succeeding 

 workers. He recognizes three great subclasses: i. Coniocarpi; 2. Disco- 

 carpi; 3. Pyrenocarpi. 



The Coniocarpi are a group apart, but as their fruit is at first entirely 

 closed at least in some of the genera the more natural position for them 

 is between Discocarpi and Pyrenocarpi. It is in the arrangement of the 

 Discocarpi that variation occurs, Reinke's arrangement of orders and 

 families in that subclass is as follows : . 



Subclass 2. Discocarpi. 



Order I. GRAMMOPHORI: Fam. GRAPHIDACEI and XYLOGRAPHACEI. 

 1 Reinke 1894, '95, '96. f Darbishire and Fischer-Benzon 1901. 



