112 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



Fiff. 4. A longitudinal section of Sigillaria vascularis, from the central axis to 

 the exterior of the stem, showing the structure of the plant ; magnified 

 12 diameters. 



a a. The central axis composed of large vessels, barred on all their sides 

 by transverse striae. 



a' a'. The smaller vessels, divided into parts by horizontal and oblique 

 divisions. 



h h. The vascular cylinder of wedge-shaped hexagonal vessels, barred on 

 their sides by transverse striaj. 



d d. Traces of "the vascular bimdles of vessels communicating from the 

 centre to the leaves. 



//. Coarse cellular tissue, arranged without order. 



g g. Elongated tissue or utricles arranged in radiating series, forming 

 the imier bark. 



h h. Coarse cellular tissue, forming the outer bark. 

 Fig. 5. A tangential section of Sigillaria vascularis at right angles to the outer 

 radiated cylinder, showing the vascular bundles of vessels, d d, tra- 

 versing the elongated tissue or utricles, //; magnified 12 diameters. 

 Fig. 6. A transverse section of a portion of the outer radiated cylinder of Sigil- 

 laria vascularis, showing the vasciilar biindles, d d, passing through 

 the scar into the leaf; magnified 25 diameters. 



Plate Y. Sigillaria vascularis. 



Fig. 1. Specimen (No. 2) of this stem in its calcified state, showing portions of 

 its external surface and internal bark, displaying the vascular bundles of 

 vessels, d d. 



Fig. 2. Transverse view of the same specimen, showing the central axis, woody 

 cyKnder, and bundles of vessels placed on the outside of the latter ; 

 magnified 12 diameters. 



Fig. 3. Longitudinal section of the same specimen, showing the vessels of the 

 central axis, a a, the small vessels of very delicate tissue, a" a", some- 

 times enclosing portions of barred vessels, and the small barred vessels 

 of the woody cylinder, b b ; magnified 12 diameters. 



Fig. 4. Longitudinal section of a portion of the same specimen, showing the 

 small vessels, a" «" ; magnified 25 diameters. 



Fig. 5. Tangential section of the same specimen, showing the small vessels tra- 

 versing the woody cylinder, b b ; magnified 25 diameters. 



■ 

 Plate VI. Lepidodendron vasculare. 



Fig. L Specimen (No. 3) of a stem of Lepidodendrooi vasculare in a calcified 

 state, showing portions of the external surface and its scars, as well 

 as a portion of the inner bark, with the vascular bundles of vessels, 

 d d, traversing it. 

 Fig. 2. Transverse view of the same specimen ; magnified 3^ diameters. 

 Fig. 3. Portion of the same transverse section of the stem ; magnified 12 dia- 

 meters. 

 The central axis, composed of large barred vessels, a a. 

 a' a\ The smaller vessels, divided into parts by horizontal and oblique 



divisions. 

 d d. Traces of the vascular bundles of vessels communicated from the 



centre to the leaves. 

 //. Coarse cellular tissue, arranged without order. 

 g g. Elongated tissue or utricles arranged in radiating series, forming 



the inner bark. 

 h h. Cellular tissue, forming the outer bark. 

 Fig. 4. A longitudinal section of the Le^pidodendron from the central axis, showing 

 the structure of the plant; magnified 12 diameters. 

 The letters indicate the same parts as in fig. 3. 

 Fig. 5. A tangential section of the coarse cellular tissue, ff, traversed by the vas- 

 • cular bundles of vessels communicating from the central axis to the 



leaves ; magnified 12 diameters. 



