90 FOSSIL PLANTS. 



fine parenchyma, on which are dotted numerous mouths of vascular bundles, enveloped 

 in orthosenchyma, similar to those found in Lepidodendron previously described. 

 Outside of the above-named line, where the parenchyma appears stronger, and its cell- 

 walls thicker, it seems gradually to pass into elongated utricles (or tubes), and to assume 

 at the edge a radiating appearance. In the specimen there appears to be only a little 

 coaly matter near the upper part on the right hand side of the finger, the other portion 

 probably having been removed. The transverse section, on the whole, is like that of 

 Lepidodendron ; and the great value of the specimen is the perfect preservation of the 

 delicate parenchymatous tissue surrounding the woody cylinder, and so generally absent 

 in woods of this description. It supplies a part wanting in a valuable specimen (No. 35), 

 to be hereinafter described. 



Fig. 2 (magnified four diameters) represents a longitudinal section of a portion of the 

 same specimen, showing the medulla {a), composed of orthosenchymatous tissue, in a 

 beautiful state of preservation ; the woody cylinder, formed of scalariform utricles or 

 tubes (b), the fine scalariform tubes or utricles (c), from which proceed the large vascular 

 bundles (d), composed of scalariform tubes, enveloped in a zone of fine orthosenchymatous 

 tissue, traversing the parenchyma (e), and leading to the rootlets. Two of these 

 bundles are seen going down from the woody cylinder on the left hand side, and one on 

 the right hand side. The woody cylinder has been displaced, in this specimen, from its 

 original position, and now appears sloping instead of vertical. On the extreme edge of 

 the fossil there is evidence of some traces of the elongated utricles or tubes (/), the 

 occurrence of which has been previously alluded to in the description of the transverse 

 section. 



Fig. 3 (magnified eight diameters) exhibits a longitudinal section of a portion of the 

 medulla (a), the woody cylinder (b), and the darker zone (c), whence the vascular bundles 

 {d) appear to originate, all in a most beautiful state of preservation. 



Fig. 4 (magnified twenty-five diameters) gives a transverse section (nearly at a right 

 angle) of one of the vascular bundles, enveloped in a zone of orthosenchyma near the 

 outside of the specimen. This, in all its parts, is scarcely to be distinguished from the 

 vascular bundle taken from the same part of Lepidodendron, and hereinbefore described 

 and figured in page 79, PL XIII, fig. 5, or from a similar vascular bundle in Stigmaria. 



§ 2. Specimen No. 35, JIalonia regularis. Plate XVI, figs. 1 — 5. 



• ?*■ 



Specimen No. 35 (PI. XVI, fig. 1, natural size) represents an example of Halonia 

 regularis, from the Upper Brooksbottom seam of coal in Lancashire, marked * in 

 the section of strata previously given at page 12 of this Monograph. It is imbedded in a 

 matrix of limestone, and has only a part of one side exposed. The specimen is one and 

 three eighths of an inch long ; and its section is irregularly oval, measuring one and one 



