236 PROCEEDINGS OF THE AMERICAN ACADEMY 



Tribe II. LECIDEACEiE, Fr. 



XII. STEREOCAULON, Ach. 



Apolhecia placed upon a thalline stratum, which forms a more or 

 less evident, evanescent (spurious) thalline margin, becoming plane, 

 with an obscure proper margin, and at length cephaloid and immargi- 

 nate, solid. Thallus vertical, caulescent, mostly solid {podetia), sup- 

 porting a horizontal, squamulose-granulose thallus, and arising some- 

 times from a horizontal, adnate, granulose thallus. 



The apothecia are often quite those of Parmelia, but they also occur 

 subimmarginate from the tirst, or with only an obscure proper margin, 

 as observed by Schserer and Eschweiler, and the genus seems properly 

 nearest to Biatora, and related through this to Lecidea. In this view, 

 Cladonia must be taken for the highest type of Lecideacese ; and the 

 fistulous podetium, analogous certainly (Fr. Lich. p. 14) to the tubulose 

 thallus of some Cetrarije, and in Cladonia turgida, if I am not mistaken, 

 evidently formed by constriction of the ascending foliaceous thallus of 

 that species, must be considered as indicating a higher rank than the 

 solid podetium ; this last being rather a branched stipe, as is suggested 

 by a comparison of Stereocaulon Fibula with Biatora Byssoides. And, 

 adopting a somewhat wider sense for Eschweiler's remark, that Clado- 

 nia unites in itself the horizontal and the vertical thallus, we might, in 

 the point of view that we have chosen, see reason to agree with him 

 that this genus is even the highest development of Lichenose vegeta- 

 tion ; or to venture, at least, the suggestion, that no genus, which does 

 not include the horizontal type, should seem to be the most perfect typ- 

 ical representative of Lichenes. Fries, from whose profound conclu- 

 sions we are far from prepared to depart, attributes indeed to Usnea 

 (1. c. pp. 9, 17, 198) the highest rank, and, where he considers the 

 genera as falling into parallel series, he, in this view, assigns the posi- 

 tion to Usnea, Stereocaulon, and Sphserophoron. But if there is evi- 

 dently a distinction between the highest typical development and the 

 highest actually attainable development, and the former represent the 

 most perfect condition of the plant, or genus, per se, as a distinct real 

 or assumed existence in nature, — as the latter is representative of ex- 

 treme tendencies of the vegetation in question to ascend to a higher 

 than its typical structure, — Usnea, &c., may be taken as representing 



