230 CONIFEBALES [CH. 



bordered pits large, approximately 25 \L in diameter, in 1 2 

 opposite rows, sometimes in contact and slightly flattened. 

 Medullary rays uniseriate, 1 14 cells deep, also fusiform rays 

 containing a horizontal canal ; 2 or 3 large oval pits occur on the 

 radial walls of the ray cells and in a few cases pits on the tangential 

 walls. Ray-tracheids with bordered pits occur on the edges of the 

 medullary rays. 



Among other Tertiary species reference may be made to Pity- 

 oxylon parryoides Goth. 1 from the Braunkohle of Eheinland, so 

 named from its resemblance to the North American Pinus Parry a, 

 characterised by horizontal tracheids with smooth walls and thin- 

 walled epithelial cells ; also Pityoxylon pineoides Kraus 2 a Sicilian 

 Tertiary species without ray-tracheids. 



Pityoxylon succinifer (Goeppert). 



This species from the Oligocene amber beds of the Baltic coast 

 was first named Pinites succinifer 3 and several years later fully 

 described and admirably illustrated as Pinus succinifer*. It 

 affords a striking illustration of the possibilities of amber as a 

 petrifying agent and shows several features of anatomical interest. 

 The roots are represented by pieces of wood in a pathological 

 state : the tracheids have 1 3 rows of pits on their radial walls 

 and some of them contain tyloses ; the walls of the ray-tracheids 

 have dentate ingrowths. The stem and branch wood is more 

 complete. Sieve-tubes and sieve-plates are exceptionally well 

 preserved and both cortex and pith tissues are represented. The 

 tracheids have 1 2 rows of separate pits ; a spiral sculpturing 

 on the walls of the tracheids was mistaken by Menge for the 

 spiral bands characteristic of the Taxineae and he named the 

 species Taxoxylum electrochyton. Conwentz describes tyloses in 

 the tracheids, also a crescentic patch of parenchyma in the wood 

 passing into a mass of resin 5 , a feature occasionally seen in recent 

 wood. The medullary rays have 1 4 pits in the field ; both ray- 

 tracheids and horizontal resin-canals occur and in some cases 



1 Gothan (09) p. 523, figs. 35. 



2 Kraus (83) p. 83, PI. i. figs. 13. 



3 Goeppert (41) p. 39; Goeppert and Berendt (45) A. p. 61. 



4 Conwentz (90) A. p. 26, with numerous plates. 



5 Ibid. (89) ; (90) A. p. 48 ; cf . Hollick and Jeffrey (09) B. PL xxi. fig. 4. 



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