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 POLYPORUS  ABIETINUS. 
 POLYPORUS abietinus ;  pileo resupinato  demum reflexo tenui coriaceo villoso albido obscure zonato,  
 poris irregulariter sinuato-dentatis subviolaceis.  Grev. 
 POLYPORUS abietinus.  Fries Syst. Mycol. vol.  1. p.  370.  Grey. Fl. Edin.  ined. 
 BOLETUS abietinus.  Dicks. Crypt. Brit. fase .  3.  af. 9 - f  9 •  Pers.  Obs. Mycol.  vol.  1. p.  24.  Syn. 
 Fung. p.  541.  Alb. et Schzo.  Conspect.  Fung.  Nisk. p.  254.  With. Bot. Arr.  ed. 6.  
 vol.  4. p .  396.  Decand. Fl. Fr. vol.  6. p.  40.  Purt. Midi.  Fl. vol.  3.  p.  242.  t.  13.  
 BOLETUS purpurascens.  Pers. Obs. Mycol. fa se .  1. p.  24. 
 BOLETUS purpurascens.  Decand.  Fl. Fr. vol.  6. p. 41.  (not of Pers.) 
 BOLETUS decipiens.  Liljebl. (fid. Fries.) 
 BOLETUS incarnatus.  Sêhum.  Scell. p.  391.  Hornnem.  Fl. Dan. t.  1298. 
 AGARICUS decipiens.  Wïlld.  Bot. Mag.  4. p.  12.  t.  2 . f .   5. 
 HYDNUM parasiticum.  Linn.Sp. PI.  1648.  Pentagnce Bot.  vol.  5. p.  2124. 
 HYDNUM decipiens.  Schrad.  Spic.p.  180.  Decand. Fl.  Fr.  vol.  2. p.  112.  Ejusd. Syn.p.  23.  
 SYSTROTREMA violaceutn.  Pers.  Syn. Fung. p.  551. 
 C lass  a n d  O r d e r .  CRYPTOGAMIA  FUNGI. 
 [N a t u r a l  O r d e r .  FUNGI,  Juss., Decand, Hook., Grev.] 
 G e n . C h a r .  Hymenium cum p ile i  su bstantia homogeneum e t  concretum, poris  subrotundis, dissepimentis  tenui-  
 b us simplicibus in structum.  Pileus subcarnosus vel  suberosus,  plerumque  subsessilis,  su bstantia fibrosa,  sicca*  
 Velum nullum.  Fries. 
 G e n .  C h a r .  Hymenium  (fructiferous  portion)  o f  th e  same  substance  as  the  pileus,  n o t separating  from  it,  furnished  
 with roundish  pores,  and  thin  simple  dissepiments.  Pileus somewhat  fleshy  o r corky,  generally  n e arly  
 sessile,  th e   substance fibrous a n d   d ry .'  Veil none. 
 P il e u s  coriaceus, conflu.ens, tenuis, primum resupinatus,  
 demum  reflexus,  duas vel  tres  uncias  latus,  albo-  
 cinerascens,  zonatus, villosus, margine  ssepissime  
 undulatus. 
 P o r i   ju n io re s  subrotundati,  integri,  demum  dentati  
 atq u e  irregulariter la c e ra ti;  Substantia membra-  
 nacea,  te n u is ;  Co lo r pallide purpurascens, sicci-  
 ta te  magis fiiscescens. 
 S e m in a  minutissima,  pellucida,  alba. 
 P il e u s  coriaceous,  confluent,  thin,  a t first  resupinate,  
 afterwards  reflexed,  two  o r  three  inches  broad,  
 o f   a  whitish  grey  colour,  marked  with  zones  o r  
 concentric  circles,  villose,  th e   margin  often  
 waved. 
 P ore s ,  th e   younger  ones  roundish,  en tire,  a t  length  
 toothed  a t  th e  margin, and  irregularly lacerated ;  
 Substance  membranaceous,  th in ;  Colour  pale  
 purplish, when d ry  becoming  brownish. 
 Spo r u l e s   very minute,  pellucid, white. 
 Fig.  I,  2.  Plants,  natural size.  Fig.  3.  The  mode  of  growth  when  the  plant  occurs  on  a  horizontal  surface, 
  as beneath  prostrate trunks of trees.  Fig. 4.  A mature plant, magnified.  Fig. 5.  Young plants in different  
 stages, magnified.  Fig.  6.  Pores of  a mature plant, magnified.  Fig. 7.  a. The  slightly  branched  filaments  observed  
 in the  earliest state of  the  plant,  particularly when it occurs  between  the  bark and  the wood of  decaying  
 trees,  b.  The filaments when  they first begin to assume a determinate  arrangement,  as  in  the least Jig.  a t 5.—   
 a.  and  b.  highly magnified.  Fig.  8.  The  filaments of  old macerated tubes, highly magnified.  Fig.  9.  Seeds or  
 sporules ditto, which do not appear to be numerous. 
 The great change of  form which  the  pores of  this species undergo in  the course of  a short period,  added  to a  
 . slight variation in the pileus,  has given rise to much  uncertainty respecting its genus :  a striking proof of this fact  
 is,  that Persoon has described it in  his Synopsis Fungorum,  both  as a Boletus and  a Systotrema.  Under the specific  
 name of  decipiens it has  been alternately referred  to Agarieus, Hydnum,  and Boletus.  Decandolle,  in  the  
 second  volume of  the Flore  Française,  has given it  to  the  public  as a  Hydnum,  and in  the  supplement, or sixth  
 volume, describes it a second time as Boletus abietinus, to which  he correctly adds Boletus purpurascens of Persoon  
 as  a  synonym.  I t is however  not a little singular,  and  illustrative  of  the Proteus  character of  the pores of  this  
 plant,  that in  the  species immediately following,  considered new,  and  named  by  him purpurascens,  he should describe  
 our species  a third  time,  and  so minutely and accurately that no doubt can  be entertained on  the subject. 
 In  the first' stage of  existence of Polyporus abietinus,  nothing is visible  but a minute byssoid  tuft,  extending its  
 pure white filaments in a radiating direction.# After'it has attained  the diameter of  about half  an  inch,  the first  
 traces of pores begin  to make their  appearance,  of  a  beautiful  pink  or  purplish colour ;  these  are  at their  commencement  
 nothing more than shallow cells of a roundish  form ;  they quickly change, become irregular, one-eighth  
 of  an inch in depth,  and  somewhat confluent.  Many are  not unfrequently  divided at half their  depth.  When  
 mature,  the pores are brownish in the centre of  the larger individuals,  but of  a  pale violet  towards  the margin of  
 the pileus, and nothing can be  more unequal  than  the appearance  they present,  particularly  in  the centre (for at  
 the margin  they generally preserve  the character of true pores).  At a first view, in numerous  specimens,  they are  
 more like  lamellar processes  arising from  the pileus  than  tubes  or  pores ;  but in  most  instances  they resemble  
 winding channels, with the remains  of divided dissepiments projecting from  their sides, thus giving them  a dentated  
 appearance ;  in short,  the whole seems as if  it had  been lacerated  in  all  directions  by  a contraction  in  the  plant,  
 probably the result of exposure to a hot sun. 
 The pileus in its early  state is always adnate, and  often  retains  this character.  The upper part of  many,  however, 
  becomes  reflexed and  undulate.  The substance is  very thin and  coriaceous ;  the upper surface white, villose,  
 or rather cottony,  and marked with  a few somewhat depressed  zones. 
 In  decay the whole  plant dries up, the pores become reddish brown, and sometimes almost colourless ;  the white  
 surface often tinged with dirty green., 
 I t frequently grows singly  and of a round form, but is often confluent, and  then covering a space of some inches  
 wide by a foot in length.  When confluent, however,  the determination  to a circular form is  perceptible in  the individuals  
 forming the general mass.  Its duration is  at most six months. 
 This  plant is found  in  the autumn, winter, and spring months,  on various  species of Fir in  a state of decay, particularly  
 on  dead  stems of Pihus L arix  and P.sylvestris,  both of England and  Scotland.  Mr. Greville speaks  of  
 it as common  about Edinburgh,  and my friends  Dr.  Rennie and Mr. Scoular find  it about Glasgow. 
 For all the above synonyms and descriptions, as well as for  the exquisite drawing from which  the  plate  was engraved, 
   I am indebted to R. K. Greville, Esq.