OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
685 
pinnules of this plant exhibit aspects which resemble those of figs. 13 & 14 in the 
closest manner, rendering the conclusion that our Oldham fossil is generically, if not 
specifically, identical with the above plant, an exceedingly probable one. 
The acceptance of this conclusion demonstrates two facts connected with the Carbo- 
niferous ferns : — first, that their vascular bundles are not necessarily, like those of 
living ferns, surrounded by a definite investing cylinder of prosenchyma ; and, secondly, 
that the prosenchymatous fibres of their subepidermal tissues (the sclerenchyma of 
authors) do not, as in recent ferns, constitute an uninterrupted investing layer, but 
that it is broken up into a network of fibrous bands arranged longitudinally, and 
through the long narrow meshes of which some of the parenchymatous cells of the 
middle bark reach the epidermal surface. We shall find these two facts of importance, 
throwing light upon some other examples awaiting examination. 
One of the earliest discovered of the plants from the rich storehouse of the upper 
foot coal-seam near Oldham was one of which Mr. Binney exhibited a section at 
the meeting of the Manchester; Literary and Philosophical Society held on January 9th, 
1872, when he proposed to give to the plant the name of Stauropteris Oldhamict. 
As in the preceding instance, I have obtained specimens of this petiole in every stage 
of growth, from the- largest examples down to the smallest twigs. One of the most 
beautiful, it is also one of the most perplexing of the plants of the Coal-measures — not 
as regards the details of its structure, since these are clearer than in most of these 
objects, but the interpretation of them presents several difficulties. The largest of the 
transverse sections (Plate LUX. fig. 20) are usually about T25 in diameter. The vas- 
cular bundle (a) consists of four clusters of vessels arranged in a crucial manner, and is 
imbedded in a mass of exceedingly delicate cellular tissue (g), which not only sur- 
rounds, but fills in all the intervals between the bundles. In the specimen fig. 20 
this tissue is destroyed, but it is preserved in Plate LIII. figs. 21, 22, 23, & 24 ; it is 
invested with a broad prosenchymatous layer (Jc). Plate LIV. fig. 25 is part of a longi- 
tudinal section of a matured stem. Each of the four vascular clusters consists of a 
central group of barred vessels (a) of large size, and a more peripheral series (a') of 
very much smaller ones. The largest of the inner series have a diameter of -005, and 
the smallest of the outer ones of ‘001. Both the former and the latter are barred. I 
am unable to detect any true spirals amongst the smaller series. They all pass through 
the stem with remarkable straightness and freedom from irregularity of arrangement. 
The cellular tissue which immediately surrounds the vessels (fig. 25, < 7 ) exhibits the same 
features as it does in the centre of the stem, where it partially separates the four vas- 
cular clusters. It consists of very delicate cells, elongated longitudinally, and having 
a mean diameter of *00083. Their ends are often square, but sometimes oblique. A 
casual glance at many of the specimens would almost make it appear that we have 
here a true representative of the fibrous sheath of living ferns ; but such is not the 
case. As we proceed from within outwards we perceive that this tissue passes gra- 
dually, though rapidly, into a coarse prosenchyma (h ) ; in Plate LIII. fig. 20 this 
4 z 2 
