Selaginella grandis, a native of Borneo but now widely grown in Botanic Gardens, was first described by Moore (12). It presents a number of points of considerable morphological interest which have been briefly described by various writers including Goebel (6, 7, 8), Harvey-Gibson (9, 10), Seward (13), Uphof (16), and Worsdell (18). So far as I am aware, however, no full account of the morphology of this species has hitherto been published. My attention was drawn by Professor Drummond to certain abnormal developments exhibited by the plants growing in the Botanic Garden of Glasgow, and, in an endeavour to interpret these, I was led to investigate the normal morphology of this species. Accordingly, in this memoir, the normal morphology will first be described, after which the variations from the normal and certain experimental results will be considered.

The Tertiary geology of north-western India is of particular interest on account of the extensive development of richly fossiliferous rocks of Lower Eocene (including Palæocene) age. The monographs by Cossmann and Pissarro (1909a, 1927) and Vredenburg (1928) have familiarised us with the well-preserved molluscan fauna of the Upper Ranikot beds (Palæocene) of Sind, while Lt.-Col. L. M. Davies' collection of mollusca from a slightly lower horizon in the Samana Range, on the North-West Frontier, has recently been described by myself (1930). With the exception, however, of one family, the Gisortiidæ, dealt with by Vredenburg (1927) and Schilder (1930), the mollusea of the overlying Laki group (Ypresian), as well as of the Khirthar group (Middle Eocene), have been neglected by modern workers. The well-known monograph by D'Archiac and Haime (1853–54), moreover, in which some Laki species are described, has always been a source of confusion owing to the fact that fossils from all horizons from the Danian to the Miocene are grouped together as “Nummulitic,” and no reliable information as to their respective horizons has been available.

Since 1860, in which year De Bary published his great work Die Mycetozoen, the investigation of the life-history of members of the Mycetozoa has aroused a considerable amount of interest, and a great deal of important research has been carried out in this connection. The group of organisms is particularly interesting, because it lies on the borderline between plant and animal kingdoms, and it is very possible that a detailed investigation of several species of the Mycetozoa might be of considerable assistance in elucidating certain obscure points in the life-histories of higher members of both the great natural groups. The term “Mycetozoa,” which we owe to De Bary, will be used throughout in preference to the older term “Myxogastres” invented by Fries (32, p. 2), and that of “Myxomycetes” first employed by Link (32, p. 2). “Mycetozoon,” or “fungus-like animal,” is a very appropriate description of a member of the group, since during part of its life-history it exhibits distinctly animal-like characters, and the individuals move rapidly by means of flagella, whilst later, during the development of the sporangium, a plant-like form is assumed. The combination of plant and animal characters has given rise to much discussion as to the position of the Mycetozoa in plant or animal kingdom, and the group has been claimed by both zoologists and botanists.

The paper which follows is based in the main on the magnetic records of the observatories at Lerwick (Shetland) and Eskdalemuir (Dumfriesshire), though reference is made to the data of Abinger (Surrey), Sitka (Alaska), Sodankylä (Finland), Colaba (Bombay), and Mauritius, and to records made at different times at Arctic and Antarctic stations. The situation of the Lerwick observatory, just within the auroral zone, might be expected to give to its records an outstanding value in any investigation connected with magnetic storms; the expectation has not been disappointed. The distance between Abinger and Eskdalemuir is about 470 km., and between Eskdalemuir and Lerwick about 550 km.—both quantities small compared with the dimensions of the earth—yet the mean ranges of disturbance at these three places appear to run roughly in the ratio 1:2: 4½. This at once suggests that in the extreme north of the British Isles we approach a zone of exceptional interest from the point of view of magnetic disturbance; and further,-that with suitable magnetic data some attempt might be made to compute the disturbing electric fields, at least in their main features, and possibly to arrive at some idea of any seasonal and annual changes to which these fields may be subject.

It is a familiar experience for the teacher in charge of a class dissecting Rana temporaria to notice or have his attention directed to blood-vessels in an abnormal position or absent from the place where they were expected. Sometimes, perhaps too frequently, they are ignored; but they are of interest, not only in themselves, but also because they throw light on problems that have arisen in other lines of work. From time to time such abnormalities have been reported in R. temporaria and in other Anura, but the literature of the subject is scattered in different journals.

The arrangement of the structures subserving the phenomena of the heart-beat has long been the study of anatomists and morphologists. Current descriptions are incomplete in essential particulars, and much confusion and uncertainty has arisen from the well-known fact that apparently the structures which conduct the impulses initiating muscular contraction in other parts of the body are duplicated or supported, in the heart, by a specialised mechanism. This mechanism is said to consist of atypical muscular fibres, accompanied by nerves, and arranged in anatomically distinct portions, nodal and bundle. In the nodal portions of the mechanism the fibres are smaller than those of the myocardium, and form a close entanglement, probably syncytial; while in the bundle of His the fibres vary in size in different animals. Ventricular extensions, again of widely divergent types, are well known under the name of Purkinje fibres. While two nodal portions are described, one, the sino-atrial node, at the commencement of the venous portion of the heart, the other, the atrio-ventricular node, at the end of it, only one distinctive pathway establishing continuity throughout the special mechanism has been demonstrated, namely, the atrioventricular bundle of His. Subsidiary structures of a like kind have been demonstrated, for example Kent's accessory atrio-ventricular bundle, but “no distinctive pathway between the sino-atrial and atrio-ventricular nodes has yet been demonstrated,” although the results of experiment have indicated the probable existence of such a communication (9).

The coast of Northern Trotternish has long attracted the attention of geologists for two reasons, the first being the intermittent exposures of highly fossiliferous Jurassic strata preserved below the great Tertiary lava plateau; and the second, the striking columnar sills of igneous rock which have been intruded into these Mesozoic beds. Intrusive phenomena unparalleled in Britain may be observed (preferably from the sea) from Holm to Staffin Bay, and in slightly less perfect form round the Aird to Duntulm and Camas Mòr.

Nephrolepis has generally been placed by systematists among the Davallioid ferns. The latter, which have always presented difficulties to the systematists, are divided by Professor Bower (Filicales, vol. iii, chap, xxxvii) into three groups, Nephrolepis being placed in the first of these along with Humata and Davallia. This threefold division of the Davallioid ferns was based mainly on soral characters, and the absence of critical data with regard to such characters in the genus Nephrolepis led to the present investigation.

Plant-remains have long been known to occur at a horizon near the top of the Lower Old Red Sandstone of Perthshire, far above the volcanic horizon represented in the Ochil Hills. Evans, in the Handbook of the Geology of Great Britain (1929), speaks of these Perthshire plants as occurring “near the summit of the Strathmore Sandstones”; but it is as well to remember that Evans' definition of Strathmore Sandstones is very wide, including all “beds above the Cairnconnan Grits” of Forfar. Hickling (1908) and Campbell (1913) refer to the Strathmore Beds or Group in a much more restricted sense. For them the term is a synonym for Edzell Shales, the uppermost of four divisions united by Evans as Strathmore Sandstones. On account of this uncertainty we prefer, for the present, not to employ the term Strathmore with any stratigraphical significance.

The work, of which the results are described in the following pages, was carried out in the Department of Zoology of the University of Sheffield and at the Laboratory of the Marine Biological Association, Plymouth. I wish to thank the British Association and the University of Sheffield for the use of tables at the Plymouth Laboratory, and I would also express my gratitude to Dr C. M. Yonge for much assistance, particularly for the loan of numerous papers.