harmony with the fact that adjacent cells 

 are, in this case, alike. Complex modification 

 18 here unnecessary, and adequate comparisons 

 of the secondary wood of existing primitive 

 and specialized families proves the correctness 

 of the view advanced. It is indeed a remark- 

 able fact that in woods with scalariform per- 

 forations in the vessels, the prosenchyma usu- 

 ally bears distinctly bordered pits and is thus 

 less distinct from the tracheal s^ment than 

 in case of woods in which the vessels are 

 characterized by the simple or porous perfor- 

 ations. 



A feature of interest not mentioned by Jef- 

 frey is the more or less frequent occurrence of 

 branched bars. They occur occasionally in 

 Liriodendron and other genera with scalari- 

 form perforations; but in Cheirodendron and 

 some other araliaceous woods this branching 

 of the bars in the perforation may become 

 more or less intricate. 



Comparison of such types with the scalari- 

 form wood of Cycadeoidea Dartoni has been 

 suggested by Dr. Wieland, and for the purpose 

 he has placed before me recently cut sections. 

 The preservation of this fossil is perfect. The 

 sections show the minutest detail in the pit- 

 ting of the tracheids, even under a magnifi- 

 cation of 450 diameters. The outline of the 

 pits, the pit-apertures, and other minute char- 

 acters are preserved in every detail. The 

 sides and ends of these tracheids, in both 

 tangential and radial aspects, are pitted with 

 regular scalariform bordered pits, which at 

 once remind one of those of Magnolia. Along 

 with the true scalariform pits occur a few 

 elliptical pits, and these are inserted between 

 the long pits in such a manner that, by the 

 dissolution of the borders and closing mem- 

 branes, occasional branched bars would result. 

 The resemblance between the pitting of these 

 cycadeoidean tracheids and the vascular ele- 

 ments of Magnolia on the one hand, and 



