46 



rarum, &c., tarn sibi invicem ut apparet appropinquantia, ut, qui 

 singulam in natura hand persecutus sit, omnia confluere paratus sit 

 jurare. Fr. 



7. Si rite excipere velis diversorum auctorurn judicia de singulis 

 speciebus, attendere debes ad diversum eorurn geriium; utrum 

 species ad historiam (quod nobis primarium) an e characteribus 

 distinguant; utrum ad transitus directos tantum an indirectos sive 

 obliteratione ortos simul contrahant ; utrum ad typos prsecipue, an 

 abnormes status ssque, attendant. Fr. Mant. II. 



IX. SYSTEMA. 



We may proceed in the disposition of plants in two ways, either 

 of which maybe natural or artificial, according as we distinguish or 

 confound affinity and analogy, or affinity and systematic character. 

 If we merely collect things like and related, and, variously circum- 

 scribing the sections, neglect any common principle of disposition, 

 we have &Methodus. If, on the other hand, such common principle 

 be proposed, and the whole thereto conformed, arises the Systema. 

 Examples are readily turned to: of the first, in Eschweiler's Dis- 

 position, admitting nothing higher than Tribes, under which the 

 genera are brought together ; and of the second, in the System to 

 be now set forth. Of the exclusive value of either way it is unim- 

 portant to speak ; the Method should be the foundation of the Sys- 

 tem, and the System the scope of the Method. Among the earlier 

 illustrators of the Lichenes, the thallus was primarily regarded ; 

 from this proceed the arrangements of Dilleniua and Linnaeus; 

 and in later times, of Acharius (in his Prodromus), Agardh, Delise; 

 and with some reference to the fructification, of Hoffmann, Decan- 

 dolle, Eschweiler (in his Systema), and Fee. We find, next, the 

 excipulum taken as primary, by Wahlenberg, and by Acharius (in 

 his later works). Lastly, the thalamium was assumed as primary 

 (as first by Micheli, says Fries) ; which is the principle of the ar- 

 rangements of Persoon, Schrader, Luyken, Fries, and Meyer. The 

 instructive view of the thalline or Fe'ean system, wherein Lichenes 

 are regarded as either Myco-lichenes or Phyco-lichenes ; and of 

 that of Acharius, proceeding from the excipulum, and distinguish- 

 ing them into Ccenothalami (exc. proprium), and Idiothalami (exc. 

 thallodes), which Fries has given, and which, as he presents it, is full 

 of new light on the whole order, should be here referred to. We 

 proceed now to a view of the Friesian System in detail, as it is pre- 

 sented in the Lichenographia Europea Reformata, with constant 

 reference, however, to the latest expression of it in the Flora Sca- 

 nica, and with some few other modifications which I have myself 

 been led to prefer. The principles of the Disposition were pro- 

 posed by Schrader and Luyken, as above said, and from these the 

 earlier disposition of Fries, that of Meyer, and the present, have 

 proceeded. As possibly adding somewhat to the value of what fol- 

 lows, I give, also, in their places, a list of such New England, and 

 other American species, as I am sufficiently acquainted with ; pre- 

 mising, however, that it is incomplete, that but little time has been 

 given to it, and that it is intended only for practical convenience. 



