234 
PBOFESSOR W. C. WILLIAMSON ON THE OEGANIZATION 
name of Lagenostoma. Though it is rare in our Lancashire nodules, yet it is the one 
which I have found most frequently, with the exception of the Trigonocarpon. Owing 
to their small size I found it impossible to make a linear series of sections of each seed ; 
and yet nothing could be more misleading than any isolated section is, whether longi- 
tudinal or transverse. Hence I was led to adopt what I have found to be a most useful 
method of examination. I ground down each seed slowly and with the utmost caution, 
and then carefully sketched the various characteristic appearances as they presented 
themselves during the progress of the grinding process. The adoption of this plan ren- 
dered it almost impossible for any important feature to escape my eye. At the same 
time the more important of these appearances are permanently illustrated in my cabinet 
by the adoption of another method which is rendered possible by the peculiar minera- 
lization of these seeds. On reaching any structure for which it seemed desirable to retain 
an available voucher, I affixed the surface with balsam to a microscopic glass slide in 
the usual manner. I then ground away the opposite side of the seed until I arrived at 
a repetition of the appearances on the presentation of which my first grinding had been 
arrested. Having thus obtained a second verification of these appearances I advanced 
slowly until I reached the centre of the seed, which I protected in like manner by a 
covering of balsam and thin glass. Thus many of my specimens exhibit two sections, a 
central and a tangential one, both sections being examined as opaque objects by means 
of reflected light. The various tissues being generally dark-coloured and carbonaceous, 
whilst their cavities have been filled with white, infiltrated carbonate of lime, nothing 
can be more beautifully distinct than many of these specimens are when thus examined. 
Most of the specimens have been of my own finding ; but I am indebted to Mr. Butter- 
worti-i for an example of a Trigonocarpon and a Lagenostoma , and also to Mr. Nield 
for a specimen of each of these genera, which specimens these indefatigable auxiliaries 
kindly allowed me to grind away, sacrificing their treasures in the interests of science. 
In its perfect state the seed under consideration has the form of a nutmeg, being so 
broadly ovate as to approach the figure of a sphere. Its length is about T6 and its 
breadth about T. At its upper extremity there appears to have been a slight central 
prominence, in the middle of which was the micropyle. 
The first series of figures of Lagenostoma to which I would call attention represent 
successive sections made from Mr. Butterworth’s specimen. Fig. 53 is a rather 
obliquely transverse one made near the extreme micropylar end of the seed, a is a 
part of the dense testa ; d is the uppermost extremity and central micropilar orifice 
of the peculiar flask-shaped cavity which I propose to designate the lagenostome ; at 
a' we have the opposite half of the testa detached from a by pressure, and also inter- 
sected lower down in the seed than at a. We have here some crenulated outlines, e , 
becoming separated from, the testa. In fig. 54, which is a section made yet a little 
lower down in the seed than 53, we find that the testa ( a ) has its internal surface 
regularly crenulated, whilst the lagenostome ( c ) appears as a small mass of parenchy- 
matous cells, enclosed in a firm and well-defined membrane. The crenulated arches at 
