PLATE XII. 



Fig. 37. — Part of a fragment of a Stigmarian root split vertically. Exterior 

 of the vascular cylinder, b. Rootlet bundles crossing the cortical region, /. Ex- 

 terior surface of the cortex, d, d. Half the natural size. (Page 24.) 



Fig. 38. — One extremity of Fig. 39, b. Vascular wedges, b, of the cylinder 

 separated by primary medullary rays, b'. The central medullary cavity is occupied 

 by an intruded Stigmarian rootlet, in the interior of which the rootlet bundle is 

 preserved. Nat. size. Cabinet, No. 867. (Page 24.) 



Fig. 39. — Side view of Fig. 38, with numerous rootlet bundles, /, enclosed 

 within their several bundle sheaths, issuing from the primary medullary rays of 

 the cylinder. Nat. size. Cabinet, No. 867. (Pages 24, 26.) 



Fig. 40. — Fragment of a large nodule enclosing a disorganised Stigmarian root, 

 almost identical with one of which the specimen, Figs. 38, 39, is the vascular 

 cylinder, d represents a cast of the outer surface of one side of the root, with 

 casts of the basal ends of the rootlets penetrating the stone. Rootlets from the 

 opposite side of the root are seen at g, g, with their free ends pointing to the right. 

 /, a mass of rootlet bundles resembling those given off from the exterior of Fig. 39. 

 (Pages 24, 39.) 



Fig. 41. — Inner surface of a fragment of the outermost bark, with rootlet 

 bundles penetrating it to reach the rootlet-scars existing on the reverse side of the 

 specimen. (Page 25.) 



Fig. 70. — Fragment of the vascular cylinder of a Stigmaria, upon both surfaces 

 of which the bases of rootlet-scars have been impressed on the disappearance of 

 all the other cortical tissues. Nat. size. Author's Cabinet. (Page 37.) 



Fig. 72. — Cast of the outer surface of a fragment of Stigmarian bark with 

 undulating corrugations. Nat. size. Museum of the Owens College. (Page 38.) 



Fig. 74. — Fragment of Stigmarian bark in which the bases of the rootlets are 

 preserved as funnel-shaped depressions, within which the outer cortex of the rootlet 

 forms a prominent ridge at g, and the conical apex of the rootlet cushion is seen at 

 the bottom of the funnel, h. Nat. size. Author's Collection. (Pages 38, 40.) 



Fig. 76. — Diagrammatic section of a Stigmarian rootlet attached to its bark, 

 d', d", illustrating Figs. 74 and 75. Inner surface of the parenchymatous layer of the 

 bark, d'. Outer surface of the same, d". Small remnant of the outer cortex of the 

 rootlet, g", g", being the point near which the rootlet, g, had been broken off 

 from its basal end. Cylindrical interior of the base of the rootlet, g', corresponding 

 to the funnel-shaped depressions, h, of Fig. 74, and to the central prominences of 

 Fig. 75. Apex of the cone of the rootlet cushion, h, forming the apical depression 

 of each central prominence of Fig. 75. (Page 39.) 



