108 



DESCRIPTIVE CATALOGUE 



show protoxylems with undoubted tracheids lying towards the 

 pith within them. The protoxylem elements which are recog- 

 nisable in longitudinal sections, have fine, close, spiral, approxi- 

 mating to scalariform, thickening. In the transverse section, 

 groups of small elements, about four or five deep, lie on the 

 internal side of the protoxylems ; they may consist only of 

 " bundle sheath," or may possibly contain a few centripetal 

 xylem-elements. So far as we can judge from the transverse 



Text-fig. 26. PUyoxylon Benstedi, sp. nov. Longitudinal section showing 

 resin-canal filled with tyloses, t., and with tbick-walled pitted epithe- 

 lium cells, e. No. 38353 B e. 



sections, there certainly seem to be a few centripetal xylem- 

 cells. 



In the secondary ivood the annual rings are sharply marked, 

 the tracheids of the spring wood being about 25 x 30 p to 30 x 

 35 /A in diameter, and those of the autumn wood about 15 x 20 fj 

 to 19 x 25 p. The thickness of the wall in the last /.ones of 

 autumn wood is about 5 ju, thus nearly as great as the diameter 



