OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
235. 
e, springing from the portion of the testa at a', have now increased in size. Fig. 55 is 
the third of this descending series of sections. We now see that two of the crenulations 
of the testa, at e, e, are assuming the form seen in fig. 53, e , whilst those at d have now 
wholly detached themselves from the testa, a!, with which they were connected in figs. 
53 & 54. The fourth section (fig. 56) now shows the testa a as a strong well-defined 
membrane of uniform thickness, whilst the crenulated outlines, e, of fig. 55 are now yet 
more entirely separated from the testa. 
The value of this unique, though crushed, fragment lies in the clear proof which it 
affords us that the remarkable structure e, d, which I propose to designate the canopy 
of the lagenostome , originates superiorly in the hard testa of the seed. Fig. 57, which 
represents a portion of the testa a , with the crenulations of the canopy e intermediate 
between the sections figs. 55 & 56, further demonstrates the origin of some other curious 
structures seen in sections to be described. At a ' a cross bar of the testa unites that 
structure with the centre of each of the crenulated curves of the canopy e. In 
the other crenulations this bar is imperfect, only projecting from the testa like a 
tooth and not reaching the concavity of each crenulation. It is now, in fact, a small 
projecting ridge running down the inner surface of the testa, but which has disappeared 
before reaching the section 56, a. Figs. 58, 59, 60, & 61 represent a series of four ver- 
tical sections of another specimen made in parallel planes. Fig. 58 is made nearly 
midway between the most prominent lateral surface of the seed and its centre. Fig. 59 
is made midway between fig. 58 and fig. 60, which latter has been carried exactly through 
the central axis of the seed ; whilst fig. 61 is from a plane nearly corresponding with 
fig. 59, but on the opposite side of the seed to the latter section. Fig. 58 exhibits the 
testa a, which appears to have been a hard, dense, sharply defined structure, having a 
thickness of from -01 to ’005, but usually having a mean thickness of *006. I have not 
been able accurately to detqgpine its composition, but there are indications that it con- 
sists of an assemblage of oblong cells. Immediately within it is a second and much 
thinner membrane f, but which obviously has adhered closely to the inner surface of the 
testa, as is shown by the numerous irregular shreds of tissue which still link the two 
together. I have designate# this the nucular membrane. This term seems conveniently 
to represent M. Brongistiart’s term “ membrane nucellaire.” Within this again is the 
third membrane g , which is also extremely thin. This I regard as the membrane imme- 
diately investing the endosperm, the “ membrane perispermique ” of M. Brongniart. 
In fig. 59 all these tissues reappear at the lower part of the seed, as in fig. 58 ; but 
at its upper part we find new conditions. The endospermic membrane g is there removed 
much further from the testa than at its opposite end. The nucular membrane/ 1 splits into 
two portions at f',f. The outer layer, e, e, ascends towards the upper part of the testa, 
where it is inflected into four or five crenate curves, the concavities of which are directed 
towards the inner surface of the testa, the outermost ones on each side being the largest. 
Within this structure, which I have designated the canopy , we find another space partly 
filled by a very delicate parenchyma, h, and enclosed superiorly by the innermost, c, 
of the two layers into which the nucellar membrane splits at/',/'. 
