STIGMARIA 



243 



which the principal rays occupy the meshes. Through- 

 out almost the whole thickness of the woody zone, a 

 regular radial arrangement of the elements prevails ; 

 there is no sharp distinction between primary and 



Fig. 98. — Stigmariaficoides. Transverse section of a small specimen. _*-, zone of wood, 

 radially seriated throughout ; c, middle cortex, only partially preserved ; pd, peri- 

 derm ; c 2 , outer primary cortex ; c^ t hypodermal zone of cortex ; rt, bases of 

 rootlets ; free rootlets are also shown. X 3^. From a photograph by Mr. L. A. 

 Boodle. Spencer Coll. r47 (now S. Coll. 146s). 



secondary xylem, but at the inner end of each wedge 

 the elements are smaller and less regular than elsewhere. 

 Good radial sections show that the spiral tracheides arc 

 placed at the extreme inner edge of the wood, next the 

 pith, so that centripetal wood in this form of Stigmaria 

 was entirely absent. This is a rather surprising 



