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PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION

name of Lagenostoma. Though it is rare in our Lancashire nodules, yet it is the onewhich I have found most frequently, with the exception of the Trigonocarpon. Owingto 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 usefulmethod of examination. I ground down each seed slowly and with the utmost caution,and then carefully sketched the various characteristic appearances as they presentedthemselves 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 sametime the more important of these appearances are permanently illustrated in my cabinetby 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 retainan available voucher, I affixed the surface with balsam to a microscopic glass slide inthe usual manner. I then ground away the opposite side of the seed until I arrived ata repetition of the appearances on the presentation of which my first grinding had beenarrested. Having thus obtained a second verification of these appearances I advancedslowly until I reached the centre of the seed, which I protected in like manner by acovering of balsam and thin glass. Thus many of my specimens exhibit two sections, acentral and a tangential one, both sections being examined as opaque objects by meansof reflected light. The various tissues being generally dark-coloured and carbonaceous,whilst their cavities have been filled with white, infiltrated carbonate of lime, nothingcan 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. Lutter-worth for an example of a Trigonocarpon and a Lagenostoma , and also to Mr. Nieldfor a specimen of each of these genera, which specimens these indefatigable auxiliarieskindly 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 sobroadly ovate as to approach the figure of a sphere. Its length is about T6 and itsbreadth about - 1. At its upper extremity there appears to have been a slight centralprominence, in the middle of which was the micropyle.

The first series of figures of Lagenostoma to which I would call attention representsuccessive sections made from Mr. Lutterworth’s specimen. Fig. 53 is a ratherobliquely transverse one made near the extreme micropylar end of the seed, a is apart of the dense testa ; d is the uppermost extremity and central micropilar orificeof the peculiar flask-shaped cavity which I propose to designate the lagenostome; ata! 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 littlelower down in the seed than 53, we find that the testa ( a) has its internal surfaceregularly 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