The district examined in the course of the research embodied in this paper is the south-eastern part of the county of Fife, lying between the coast-towns of Aberdour and Kirkcaldy, and stretching inland to a roughly semicircular boundary enclosing Auchtertool, Raith and Chapel. The area within these limits, amounting to approximately 30 square miles, was mapped on a scale of 6 inches to a mile, and the chief results of the field-work are shown in the map on Plate III.

In his Presidential Address to the Royal Society of Edinburgh in October 1920, Professor Bower (2) called attention to the question of Size in relation to stelar morphology, and advanced evidence (with particular reference to the Filicales) to show how the principle of similar structures has affected the internal morphology of the vascular system of plants. In dealing with the application of this principle he remarks that “the stems and roots of most plants are approximately cylindrical. The same is the case as a rule for their conducting tracts also. The cylinder is one of those solid forms in which the proportion of external surface to bulk is exceptionally low. Any deviation from the cylindrical form, either by external projections or by involutions, necessarily leads to an increase in the proportion of surface to bulk. The surface varies only as the square of the linear dimensions, but the bulk as the cube. It follows, therefore, that in carrying out any of those physiological functions of a living organism which depend on surface, as do all those of the acquisition and inter change of material, the actual size of the part which exercises that function is a matter of the greatest moment. The larger the plant is, the more dependent will it then be upon its form and detailed structure, not only for its stability, but also for the performance of its functions of absorption and transit of liquids and gases. This will apply not only to the external surface, but also to those internal surfaces which limit one tissue tract from another.” In illustration of this, examples were taken from the stems, tubers, and petioles of the Filicales, and the size-factor was also found applicable to the large prop-roots of palms, such as Areca and Verschaffeltia.

This memoir is based upon the study of three normal human embryos belonging to the period of development preceding the cleavage of the paraxial mesoderm into the primitive segments, as well as of certain abnormal specimens of the same early period which have yielded valuable corroborative data, but will not be described in detail. Well-preserved specimens belonging to these early stages are very rare, and our knowledge has been, and can only be, built up from the detailed descriptions of isolated cases by the individual observers into whose hands they happen to fall.

During the last few years Dr R. Kidston, F.R.S., has kindly entrusted to me for investigation certain specimens of fossil plants, showing structure, mostly from Lower Carboniferous horizons in Southern Scotland.

Four of these plants are dealt with in the present communication, namely:

Calamopitys radiata, sp. nov.

Calamopitys zonata Kidston, in MS. (now Endoxylon zonatum).

Bilignea solida Kidston.

Bilignea resinosa, sp. nov.

It will be understood that all the specimens were in Dr Kidston's hands in the first instance; the sections were cut under his direction, and he himself had determined the chief points in the structure of each before I began my observations. It only remained for me to work out the details, and to form my own views as to the probable affinities of the plants.

The deposits of the Devonian period over a large area in the interior of North America to the south of the great lakes are known to be wholly of marine type and to have continued those of the Silurian period. They were formed in a great gulf open to the south. Along the western border of this gulf shore-deposits and, during Upper Devonian times, deposits of Old Red Sandstone type were accumulated, while in the middle of the gulf the resulting rocks were limestones and shales. In Ohio, following on a narrow band of what is regarded as Oriskany Sandstone (Lower Devonian), the Corniferous limestone and some local representatives of the Hamilton formation represent the Middle Devonian. Above this comes a great mass of black shale, which here represents the whole Upper Devonian and may continue up into black shales of the Lower Carboniferous. A black shale at the base of the Upper Devonian rocks has an extensive range in the central region of North America, being represented by the Huron shale in Canada and the Genessee shale in New York. Drifted land plants from the coast of the gulf, or from islands in it, have been found in the black shale and also in the underlying Corniferous limestone, and some other fossils are commonly spoken of as Algæ but have afforded little or no botanical information.

In 1897, a description was given of a silicified specimen from the Old Red Sandstone of Reswallie near Forfar which was named Cryptoxylon Forfarense. In this note evidence is brought forward for placing the plant in the genus Nematophyton.

For an account of the specimen and of its structure reference may be made to the original description and the figures, which are based on photographs. The stem was shown to consist of an apparently parenchymatous tissue, in which groups of smaller cells occurred. These isolated groups form dark spots, which are arranged concentrically in the transverse section and are slightly elongated in the longitudinal direction. In discussing the affinities of the plant it was noted that it appeared to be essentially distinct from Nematophyton, since in that plant the tissue is entirely composed of long tubes.

The origin of the name “Uist” or “Vist” is uncertain. It is probably either of Pictish or Scandinavian derivation. It is said to be found amongst the names of the early Pictish kings. Some authorities give “Ivist” as the earliest known name, and this may mean “Ey-vist,” the Island of Vist (the Pictish king), or may be rendered literally from the Norse as “dwelling-place.” Others believe that the name is derived from “vest” (Danish) signifying “the west island.” Originally Uist comprised what we now know as North Uist, Benbecula, South Uist, and possibly Barra as well.

Though first described so long ago as 1842, the remarkable fossil fish named by Germar Dorypterus hoffmanni has never become well known among palæontologists. This fact, due no doubt to its extreme rarity, is exemplified in the figures of the fish which appear from time to time in text-books: there is a decided tendency for the more recent figures to show less resemblance to Dorypterus than the earlier ones. The present paper is an attempt to make the structure of this interesting fish better known. It gives the results of a study of the four known English specimens, and, as far as possible, it embodies these results in a new restoration which, it is hoped, will help towards making future illustrations of Dorypterus rather less misleading than those now current.

As is well known, one of the chief problems relating to the vertebrate nervous system is the question of its continuity or discontinuity both in the adult and in the embryo. The upholders of the latter theory believe that the neurones of the adult are not in continuity but only come into close contact by means of the synapses, while in the embryo the young nerve grows out through the tissues with a free end, and only secondarily unites with its particular end-organ. Much experimental, physiological, and pathological evidence has been brought forward in support of this view, and its upholders include most of the neurologists of the day, whose knowledge, however, relates chiefly to the higher vertebrates and who have made no, or at most very little, detailed study of the phenomena presented by the more primitive forms.

The district described is of considerable relief, according to British standards. Pitlochry lies 300 or 400 ft. above sea-level, while two summits, south-west of the River Garry, reach 2559 ft., and Ben y Gloe, north-east of the same, attains to 3671 ft. Exposures are everywhere sufficient for the mapping of groups, but they seldom permit of the following of individual beds or the recognition of the pitch of isoclinal folds.

The Geological Survey has mapped the whole district on the six-inch scale, and published Sheets 55, 56, 64, and 65 of the one-inch Map of Scotland—all except Sheet 64 accompanied by explanatory memoirs.

The ammonites dealt with in this paper belong to the family Echioceratidæ (Buckman, T.A., 1913), a varied group of slender, generally evolute forms, usually ornamented by ribs but very rarely tuberculate. In many members of the family the periphery has only a feeble keel, but in some a sharp keel, with or without sulci, may be present.

Ammonites of this family have most frequently been recorded as Ammonites raricostatus, and the raricostate species are by far the best known. The species at present classified with the Echioceratidæ, however, can be roughly grouped, with reference to their form only, as follows :—

1. Raricostate forms, with strong widely spaced ribs and feeble carina, e.g. A. raricostatoides, A. zieteni.

2. Forms with closely spaced ribs, with carina absent or feeble, e.g. A. viticola, A. prorsum.

3. Forms with elevated whorls, bearing regular ribs of moderate strength and with carina and sulci, e.g. A. aplanatum.

4. Forms becoming smooth on the last whorls, which are thin, with an acute keel and obsolescent sulci, e.g. A. macdonnellii.