[ 255 ] 



LII. Remarlcs on the Identity of certain Genei'al Lwws >which 

 have been lately observed to regidate the Natural Distribu- 

 tion of Insects and Fungi. By W, S. MacLeay, Esq. M.A. 

 F.L.S. 



[Concluded from p, 200.] 



TN the first place, M. Fries lays it down as a rule, which is 

 •*- quoted above, that he admits no groups whatever to be na- 

 tural unless they form circles more or less complete. Let us 

 then apply this rule to what he terms his central group, and 

 which he makes always to consist of two. Does this form a 

 circle ? If not, the group cannot be natural according to his 

 own definition. 



If, on the other hand, its two component groups are each 

 circles, then these are natural. Thus the Ptilota will not 

 form one circle, but two ; consequently they form two natural 

 groups, which is furthermore proved by their parallel relations 

 of analogy. If we turn to Fungi also, the Hymenini, accord- 

 ing to M. Fries, do not form one circle, but two ; one of Pi- 

 leati, the other of Clavati ; so that instead of the Hymenomy- 

 cetes forming four natural groups, viz. Sclerotiacei, Tremellini, 

 Uterini, and Hymenini, they form, if our author be correct, 

 five; viz. Sclerotiacei, Tremellini*', Uterini, Pileati, and Cla- 

 vati. 



But, to understand this still better, we had as well perhaps 

 enter a little deeper into our author's theory. Every group, 

 he says, which expresses well the character of the superior 

 group to which it belongs, is called the centrum : by this, not 

 meaning the centre of a circle, but the site of the normal form 

 or perfection of the particular structure common to the su- 

 perior group, of which it forms a part. The word j^et feet ion, 

 even as here used, requires explanation ; for it does not, as 

 might be supposed, in this place signify affinity to any parti- 

 cular group. Our author, on the contrary, most properly 

 says, that the idea of perfection in structure has nothing to do 

 with affinity f. " Ipsa haec affinitas imperfectionem potius 



indicat ; 



• This appears to be one of those hiteresting groups which connect the 

 least perfectly organized beings with those which are the most perfectly 

 organized. ' In the department of Ht/steroph/ta it is to the Coniomt/retes or 

 lowest Fungi, what in the animal kingdom the Venues are to the Acrita. 



\ To the genera! observations on this subject, as connected with the 

 animal kingdom, which I have given in Horce Entomo/ogica, p. 205, I may 

 add the botanical authority of l^rofessor Schweigger. " Nee ctiam genera 

 et ordines plantarum in lineam a cryptogamicis ad dicotyledoncas progre- 

 dientem itadisponi possunt, ut familia <|u;cvis priccedentis structuram magis 

 evolutam praebeat. Vix ullus do vegetabilium scrie usitata, acotyiedonum 

 numero dcducta, affirmat, plantas dicotyledoncas omui ratione monocoty- 



ledoncis 



