PLATE XIII. 



Lepidodendron Harcourtii. 



Fig. 1 (No. 31). A transverse section of a stem from the Coal-measures near 

 Dudley. Magnified 3f diameters. 



Fig 2. A longitudinal section (from the centre to the circumference) of the stem. 

 Magnified 4 diameters. 



In this and the following plates the same parts of the specimens figured are indicated bv 

 the same letters, as follow : — 



a. The middle part, showing the central axis or pith, composed of orthosenchyma. 

 b- The large scalariform tubes forming the inner portion of the woody cylinder. 



c. The smaller scalariform tubes forming the outer portion of the woody cylinder, 

 from which the vascular bundles communicating with the leaves or rootlets proceed. 



d. The vascular bundles, proceeding from the woody cylinder and extending to 

 the leaves or rootlets. 



e. The mass of parenchymatous tissue, at first (near to the woody axis) of a fine and 

 lax character, but increasing in size and strength as it proceeds outwards, until it becomes 

 prosenchymatous. 



/. The elongated utricles or tubes, arranged in radiating series, forming the outer 

 zone next the epidermis. 



g. The epidermis, converted into coal. 



Fig. 3. A longitudinal section of a portion of the stem, showing part of the pith, 

 the inner and outer portions of the woody cylinder, the origin and structure of the 

 vascular bundles, and the delicate parenchyma traversed by them. Magnified 7 

 diameters. 



Fig. 4. A longitudinal section of a portion of the outer part of the stem, exhibiting 

 the coarse parenchymatous tissue, gradually passing into prosenchyma, and thence into 

 elongated utricles or tubes; and the epidermis. Magnified 12 diameters. 



Fig. 5. A nearly right-angled transverse section of one of the vascular bundles, near 

 the outside of the stem, displaying the vascular axis, surrounded by a zone of orthosenchy- 

 matous tissue, then a regular circle of fine parenchyma, and the mass of coarse paren- 

 chyma in which the whole is imbedded. Magnified 24 diameters. 



Fig. 6. A transverse section of a part of the stem near the outside, showing the 

 coarse parenchyma traversed by a vascular bundle, and a portion of the outer radiating 

 cylinder, and the epidermis. Magnified 5 diameters. 



