1862.] BINNEY SIGILLARIA AND LEPIDODENDRON. Ill 



are seen some of the smaller vessels (a) a') divided by horizontal and 

 oblique partitions similar to those before mentioned as occurring to 

 a less extent in No. 2 ; but in this specimen there is no trace of the 

 fine tissue (a" a") seen in the centre of that stem. 



The tangential section shows the vascular bundles traversing the 

 cellular tissue from the axis to the leaves, in a similar manner to 

 those described in specimens Kos. 1 and 2. 



Upon the whole, No. 3 may be said to resemble Nos. 1 and 2 in 

 every respect, except that the internal radiating cylinder of barred 

 vessels is wanting in it. At first, it was supposed that this cylinder 

 might have disappeared in the cutting and polishing of the stone ; 

 so several other specimens were examined, but in all cases the 

 cylinder was found wanting; so there is no doubt that this is a 

 plant more nearly allied to the common Lepidodendron than Nos. 1 

 and 2, which it will be more convenient, for the present, to class 

 under the genus Sigillaria, on account of their internal structure, 

 notwithstanding their external characters. It is proposed to distin- 

 guish these two specimens (Nos. 1 and 2) by the name Sigillaria 

 vascidaris, from the circumstance of each of them possessing a central 

 axis composed of barred vessels, in the place of the cellular tissue so 

 generally formed in piths. No. 3 it is proposed to designate as a 

 Lepidodendron, and to give it the specific name of vasculare, from 

 the fact of its central axis being also composed of barred vessels, 

 similar to those of Sigillaria vascularis. 



EXPLANATION OF PLATES IV. V. & VI. 

 Plate IV. Sigillaria vascularis. 



Fig. 1. Specimen (No. 1) of a stem of Sigillaria vascularis in a calcified state, 

 found in the Lower Coal-measures of Lancashire, in the middle of a 

 seam of coal ; showing a portion of the exterior surface, the bark of 

 which is preserved, displaying the leaf-scars and the cicatrices which 

 characterize this genus. • 



Fig. 2. Transverse view of the same stem ; magnified 3|- diameters. 



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



Note. — The same letters indicate the same parts in this and the pre- 

 ceding figures. 

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



hexagonal vessels having all their sides barred. 

 a' a'. The smaller hexagonal vessels in the axis or pith, foimd sometimes 



interspersed amongst the larger ones. 

 a" a". Small vessels, of very delicate tissue. 

 b b. The vascular cyhnder of wedge-shaped hexagonal vessels. 

 c c. The spaces where the mediillary rays passed between the bundles on 



their passage from the centre to the leaves at the circumference. 



d. Small round bundles of fine vascular tissue, placed next the outside 



of the woody cylinder, often apparently displaced from their original 



position. 

 e e. Space where the greater part of the cellular tissue has been destroyed, 



and replaced by mineral matter. 

 /. Coarse cellular tissue arranged without order. 



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



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



i. Indication of fibro-vascular bundles, which traverse the bark to 



communicate with the base of the leaves. 



