XLIV] PITYOXYLON 221 



of a single row are in contact and slightly flattened. Feeling 

 sceptical as to the Carboniferous age of the wood I wrote to Dr 

 Conwentz who confirmed my doubts with regard to the value of the 

 evidence as to the geological horizon. Thomson and Allin have 

 shown that Penhallow's Pityoxylon cannot be accepted as trust- 

 worthy evidence of the occurrence of a Palaeozoic Abietineous 

 type. Pityoxylon chasense is not an Abietineous species ; it is 

 founded on Dadoxylon wood devoid of annual rings and without 

 resin-canals traversing the medullary rays. 



The fragments of wood from the Muschelkalk of Recoaro 

 figured by Schleiden and Schenk 1 as Pinites Goeppertianus afford 

 no evidence of Abietineous affinity beyond the occurrence of 

 separate bordered pits on the walls of the tracheids. 



Pityoxylon eiggense (Witham). 



The petrified wood first named by Witham 2 Pinites eiggensis 

 and afterwards 3 referred by him to the genus Pence was originally 

 recorded by Macculoch in 1814 from below the massive and pre- 

 cipitous ridge of pitchstone which forms a striking feature above 

 the basaltic lavas of the Sgurr of Eigg in the Inner Hebrides. 

 Lindley and Hutton 4 and Nicol 5 also gave short descriptions of the 

 structure and Miller 6 in the Cruise of the Betsey alludes to a fossil 

 trunk as 'an ancient tree of the Oolites.' The wood occurs with 

 fragmental sedimentary rocks below the pitchstone and not 

 actually in situ ; Mr Harker's thorough examination of the island 

 led him to the conclusion that the wood and associated rock- 

 fragments are derived from Jurassic (Oxfordian) strata and were 

 carried up by volcanic agency 7 . Mr Harker tells me that he has 

 never seen the Pityoxylon with any undoubted matrix adherent; 

 it occurs with wood of a different type (Dadoxylon) which is em- 

 bedded in a white sandstone agreeing exactly with the Great 

 Estuarine Sandstone of Eigg in which similar wood has been found 

 in place. It is, however, possible that Pityoxylon did not come 



1 Schenk (68) PL v. figs. 47. 2 Witham (31). 



3 Ibid. (33) A. Pis. xiv., xv. 4 Lindley and Hutton (33) A. PL xxx. 



5 Nicol (34) A. p. 154. 6 Miller (58) p. 37. 



7 Harker (06) p. 55; (08) p. 52. In these memoirs Mr Harker discusses the 

 earlier conclusions of Sir Archibald Geikie as to the geological history of Eigg and 

 gives references to previous notices of the fossil wood; Seward (II 2 ) p. 652. 



