sideration of lichens, without adding anything important to their 

 morphology. His system of classification is not especially com- 

 mendable, although it was for a time generally accepted. He 

 divided lichens into two great divisions, the Lichenes gymnocarpi 

 and Lichenes angiocarpi. The generic distinctions were based upon 

 the form and structure of the apothecia and thallus. Of much 

 greater value are the works of Eschweiler. 1 This author, whose 

 early death was a great loss to lichenology as well as to botany in 

 general, made a careful study of the apothecia and spores of lichens. 

 He was the first to call attention to the different forms of spores, al- 

 though his attempts at utilizing these spore-characters in his system 

 of classification met with little success. Fee 2 in 1824 divided 

 lichens into eighteen orders and sixty-six genera, seventeen of the 

 latter being new. The characters of the thallus were utilized in the 

 determination of the orders. His system was not favorably re- 

 ceived. Fries and Fee will again be mentioned in the following 

 period. 



In America the work of collecting and naming lichens was also 

 begun with great zeal, although the important work was not done 

 until later periods. Many of the workers of this period devoted 

 themselves to mere catalogueing. Mich an x 3 published a short list of 

 lichens (mostly new) collected in Carolina and Canada. Miihlen- 

 berg" 1 published a list of Pennsylvania lichens. Eaton 5 published a 

 list of North American lichens, likewise Torrey 6 and Halsey. 7 



In this period also appeared a number of monographs on lichens. 

 The most noteworthy were those of Acharius who elucidated the 

 genera Arthonia, Thelotrcma, Pyrcnnla, Trypctheliiuii, Caliciiiin. 

 Glyphis and Chiodecton. Floerke issued monographs on Cladonia 

 and crustaceous lichens. Schaerer wrote a valuable treatise on the 



Systema Orbis Vegetabilis. Part I. 1825. Lichenographia Europaea reformata. 

 Lund. 1831. 



1 Eschweiler, Fr. G. Systema Lichenum. Nurenberg. 1824. 



2 Fee, A. L. A. Essai sur les cryptogames ecarees exotiques officinales. Paris 

 1824. 



3 Michaux, A. Flora Boreali-Americana. 1803. 



4 Miihlenberg, H. Catalogue of the Plants of North America. Lancaster, 1813. 

 Second Edition, Philadelphia, 1818. 



5 Eaton, A. Manual of Botany for North America. Albanv. 1818. 



6 Torrey, J. A Catalogue of Plants growing spontaneously within 30 miles of New 

 York City. Albany. 1819. 



7 Halsey, A. Synoptical view of the Lichens growing: in the vicinity of the City of 

 New York. Ann. Lye. Nat. His. N. Y. i : 3-21. 1824. 



