The writer recently undertook an investigation of certain aspects of the water relationships in the gametophyte of Polytrichum (2), showing that a large quantity of water ascends through the central strand of the stem and is given off in transpiration from the leafy shoot. The experiments were later extended to the sporophyte, the transpiration rate again being measured (3). While these observations were in progress, it was suggested that it would be useful at the same time to examine in detail the structure of the absorbing organ of the sporophyte, usually referred to as the “foot,” an organ which has been defined by Hy (16) as that part of the seta which is embedded throughout its life in the tissues of the gametophyte.

The problems of regeneration, and those relating to the production of adventitious structures in general, have not been extensively studied in the Lycopodiales, although the production of adventitious structures, some of them regenerative in nature, has been recorded for all four of the living genera. Selaginella has been examined more thoroughly in this respect than the other three genera. Adventitious roots have been induced to develop from decapitated rhizophores and from isolated lengths of stem; the production of adventitious shoots from rhizophore rudiments has also been obtained by experimental methods. Goebel (7, p. 1220) has described the development of adventitious buds on the leaf bases of Isoetes lacustris, and Osborn (12) has described interesting regenerative developments from detached leaves of Phylloglossum Drummondii. A number of examples of regeneration in various species of Lycopodium has been recorded. Goebel (5, p. 46) states that the first leaves of embryo plants of L. inundatum may produce adventitious shoots. The same writer (6, p. 83) has recorded, but not described in detail, the development of adventitious outgrowths from the decapitated shoots of young plants of L. Selago and from isolated bulbil leaves of the same species. The development of adventitious buds on isolated roots and leaves of L. ramulosum has been described by Holloway (8).

While an endodermis in the leaf is a relatively rare occurrence amongst the Angiosperms, its presence has been noted as being fairly constant in a number of families; but it is only in the case of a few of these families that it has been treated in sufficient detail to indicate its representation generically. Mylius (8), in particular, has examined the foliar endodermis of the Myrtaceæ, the Onagraceæ, and the Rosaceæ; especially the latter family, in which he makes a comprehensive investigation of the genera Spiræa, Alchemilla, Fragaria, Potentilla, Rosa, Agrimonia, and Sanguisorba (Poterium) from this standpoint. An endodermis has also been recorded as present in the leaves of certain Monocotyledonous families of which the Bromeliaceæ, Orchidaceæ, and Gramineæ (tribe Festuceæ) are examples quoted by Haberlandt (4, p. 368 sqq.) from the work of Rimbach, Schwendener, and van Wisselingh.

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.

Systematists agree that the Asteropid Ostracods are closely related to the other subfamilies of the Cypridinidæ. Asterope agrees with Cypridina in the form of its antennules and antennæ, in the peculiar bottle-brush second trunk limb so characteristic of the Cypridinidæ, and, to a lesser extent, in the gnathobasic armature of its mandibles, and yet, in its mouth parts, especially the maxillules and maxillæ, Asterope differs totally from Cypridina, and, in fact, from any other Crustacean. Attempts to homologize these limbs with those of other Ostracoda have been made by many systematists, but without much success. Thus recently Skogsberg (1920, p. 39), referring to the maxillule of Asterope, states: “This far-reaching modification and the total lack of known transitional forms makes any attempt at homologization merely a caprice, at worst obviously incorrect, at best unverifiable”; and Hansen (1925, p. 69), discussing the maxillule, states that “the chitinization is weak and lobes rudimentary that it may be impossible to interpret all points with real certainty before forms intermediate between Cypridina and Asterope have been discovered—if they exist.” Despite this impasse along purely morphological lines, I think it is possible, by studying the feeding mechanisms, to establish the relationship between the Asteropid and Cypridinid constitution.

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 Kidston Collection of fossil plant slides in the Botany Department of the University of Glasgow contains a number of sections of a very notable stem labelled “Lepidodendron textum, Kidston, n.sp.” No mention is made of this species in any of Dr Kidston's publications, but the correspondence relevant to the Collection indicates the history of the slides. This may be briefly summarised.

As early as 1883, Dr Kidston had received from Mr J. Coutts two sections (Nos. 51 and 52) of this stem, which had been collected by the latter at East Kilbride, Lanarkshire, Scotland, from the Carboniferous Limestone Series of the Calderwood Beds (Hosie Limestone) in the Lower Limestone Group. Dr Kidston postponed description of this stem till he had better sections at his disposal; the specimen, however, was lost, and it was not till many years later that he rediscovered it in Dr John Young's collection in the Glasgow Municipal Museum, and had more sections cut from it (Nos. 1144–1153). No manuscript notes of Dr Kidston's descriptive of these slides have been found, with the exception of a pencilled reference in his manuscript slide catalogue, opposite Nos. 51 and 52, to the “foliar bundles—there is an appearance as if there was a development of secondary xylem, whereas the axial bundle has no secondary wood.”

The limestone to be described occurs in two separate areas (fig. 1)—one in Lower Deeside around Banchory, another in Middle Deeside around Aboyne. The whole of the Banchory and a large part of the Aboyne outcrops provide limestone types in a high grade of regional metamorphism (the associated schists contain sillimanite). In the latter outcrop the limestone has undergone thermal metamorphism at the contacts with Newer Granite intrusions. Many of the resulting hornfelses have suffered hydrothermal alterations with development of prehnite and zeolites. Newer Granite pegmatites, intruded at the time of hornfelsing, share in this hornfelsing and later hydrothermal modifications. In addition, they exercise exopneumatolytic and exohydrothermal metamorphism. Quite local metamorphisms take place at hornblende-schist and Older Granite contacts.

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.

In the course of researches on the reproductive system of Cavia attention was drawn to certain variations in the rapidity of the repair of the endometrium after parturition. It was shown by Loeb (1914) and by Stockard and Papanicolaou (1917) that in the guinea-pig there is a close correlation during the œstrous cycle between the changes in the uterus and the events in the ovaries. It happens that in practically all the animals used for embryological researches in this department the ovaries were preserved and have been serially sectioned. It seemed worth while, therefore, to work out in the material available the relations of the post-partum changes in the uterus with the conditions in the ovaries. Recent researches have brought to light further interesting correlations between the anterior pituitary and the ovaries, and indirectly with the uterus, but in the present communication no attempt will be made to deal with this larger question.

In the species Cavia the female passes into a condition of heat immediately, or almost immediately, after the birth of a litter, and pregnancy can be repeated without any interval. The new blastocysts reach the uterine cavity on the fifth day after parturition, and during the first seven days of pregnancy extensive reparative changes take place. These changes involve not only the healing of the placental site but a shedding and restoration of the epithelial lining of the uterus. As this process does not seem to have been investigated in detail in the guinea-pig, it is proposed in this paper to describe briefly the histological changes occurring in uteri at different times post partum in non-pregnant animals. It will be necessary, however, before describing the histological details of these post-partum changes to give a brief summary of the observations of other investigators on the ante-partum changes associated with the implantation of the blastocyst, the subsequent obliteration of the uterine cavity, the formation of the decidua capsularis, and the reappearance of the uterine lumen.

The first part (5) of a study of the quantitative distribution of the bottom-fauna in Scottish waters, and of the natural faunistic divisions of the North Sea and adjacent areas, dealt with the distribution of the molluscs in the North Sea. In this paper the echinoderms from the same area are treated on similar lines. In addition the natural faunistic divisions, as shown by the distribution of the dominant species of molluscs and echinoderms, and the validity of Petersen's community concept as applied to the North Sea, are discussed.

Reference should be made to the earlier paper for information concerning the methods of collecting, the area covered by the Scottish surveys, similar surveys carried out by other workers in the remaining parts of the North Sea, the number of hauls in each square, and other introductory matters.

In 1925 Professor A. E. Trueman handed to the writer a copy of Professor Bertrand's paper, “Les Zones Végétales du Terrain Houiller du Nord de la France” (1914, p. 208), with the suggestion that it would be interesting to find out whether the succession of plants in South Wales is similar to that of the North of France, and to determine whether Bertrand's zones can be applied to the Coal Measures of South Wales. Since that time every opportunity has been taken to collect fossil plants from known horizons in South Wales and other coalfields. In addition, specimens have been examined in all the important museums and private collections, and in particular in the collections of the late Dr R. Kidston, which are now preserved in the Museum of Practical Geology.

The term “Hebrides” is of unknown origin. Some authorities suggest that it meant “the islands of Brude,” called after the names of several Pictish kings. There seems also to be considerable uncertainty about the name “Lewis.” Some derive it from “Leog,” a marsh. Macculloch traced it to “Loda,” a Scandinavian deity. The name has appeared in various forms, the earliest of which appears to be “Leodus.” Another suggestion is that it may be after “Leutha,” the last of the three Pictish kings who ruled in Orkney (Mackenzie, 1903, pp. xxxvi-xxxviii).