4^ 
N. Bancroft, 
Worsdell’s view, bringing it more closely into contact with that of 
Scott. A comparative consideration of the three opinions suggests 
that the three alliances—Lyginopteridean, Medullosean and 
Cycadean—are closely related so far as their anatomy is concerned, 
and this idea is fully confirmed by an investigation of reproductive 
and foliar organs in the three groups. 
Pig. 1. —Heterangium Griev'd. A, transverse section of stem, x, central mass 
of tracheides and parenchyma; x\ secondary wood ; ic, inner cortex; or, outer 
cortex; It, leaf-traces; r, base of a root. (Adapted from Scott, “Studies.”) 
B, part of transverse section from outer region of stele, showing a primary 
xylcm strand and adjacent tissues, cp, conjunctive parenchyma. (After 
Williamson and Scott, 1895). 
