MICHIGAN ACADEMY OF SCIENCE. 



61 



divided and subdivided the genus in still other ways. For myself, no final 

 .statement seems possible at present because of lack of knoAvledge concerning 

 development in the young stages. All things considered, it seems to me that 

 our American species would better be included in a smaller number of sub- 

 genera than Fries used, or in the case of genera, less than those proposed 

 by Earle. In this respect I follow in the main the eminent English ^lycologist, 

 M. J. Berkley in his "Outlines of British Fungology,"* who divided the genus 

 into three sections. Using the PViesian nomenclature, the Compactae can be 

 considered as a fairly natural group and can be kept intact. Of the remain- 

 ing "tribes," the Heterophyllae and Furcatae can be dispensed with by 

 referring their species to the two other subgenera — the Rigidae and the 

 Fragiles. The species placed in the Fragiles fall together quite naturally, 

 and this group can be fairly easily characterized. The Rigidae include 

 species normally between the Compactae and Fragiles in their characters, 

 of which the firm consistency is believed to be more important than the 

 incurved or striate margin and forked lamellae. The character of the young 

 margin, whether incurved or straight, can, however, be used to subdivide 

 the sul)genus, and in this paper are provisionally used for this purpose. I 

 believe that future developmental studies will show this a rather important 

 character, concerning which we have no information on a number of species 

 which apparently belong to the Rigidae. Three subgenera therefore, or if 



*Berkl\v. 1860. 



