During recent years there has been a very great advance in our knowledge of the minute structure and function of the various regions and glands of the alimentary canal of the prosobranch and pulmonate gastropods, without any corresponding increase in our understanding of the opisthobranch and, in particular, of the nudibranch gut. That the emphasis should be laid on the streptoneurous and the land-living forms is obviously due to their abundance and to the fact that they include almost all the familiar types of gastropod mollusc, but it is disappointing that, at the moment of writing, there exists only one account of the histology and function of the digestive system of either a dorid or an æolid—to confine attention to the two main types of nudibranch molluscs which occur in British waters—that of Millott (1937b). This is perhaps more noticeable when it is recalled that the nudibranchs have specialised along distinctly unusual lines, many of which are intimately associated with the food and feeding habits which the animals have adopted. The æolids, it is true, have attracted a lively interest in connexion with their possession of nematocysts, but the majority of investigators have apparently been content to trace these into the cnidosacs without concerning themselves over the other constituents of the animal's food.

The publication by Kidston and Gwynne-Vaughan ïn 1912 of a memoir on Stenomyelon tuedianum Kidston marked the beginning of a proposed series, which was never continued by them, on the Carboniferous Flora of Berwickshire, based upon material collected during 1900 and 1901 from rocks of the Calciferous Sandstone Series (Cementstone Group) at various localities in Berwickshire while Kidston was working with Mr A. Macconochie of the Geological Survey. Brief notes on this material, with identifications of some of the plants found in compression form, were contributed by Kidston to the “Summary of the Progress of the Geological Survey” (Kidston, 1901, 1902 a), where he commented upon the interest and importance of the material; but beyond recording the occurrence of petrified specimens, no further description of these was given at the time. An incomplete list of anatomical species identified from this Berwickshire material was also given by Kidston at a later date (Kidston, 1923, p. 19). Some of the petrifactions, in addition to the Stenomyelon tuedianum already referred to (Kidston and Gwynne-Vaughan, loc. cit.), have been described by various writers, mostly from specimens in the Kidston Collection of Fossil Plant Slides in the Botany Department of Glasgow University, where the majority of the sections is to be found.

The following account deals with investigations pursued by the authors during the years 1931 and 1932. Pressure of other and later work precluded the possibility of the results of the investigations being published until this year. It is believed that no recent account of the cuticular-scale pattern of monotreme hairs has been published, and the authors are convinced of the desirability of such a detailed description. When this work was commenced it was intended to be the first of a series of investigations into the scale- pattern of mammalian hairs. Hitherto work in this direction has only taken the form of either a consideration of one species only, or generalisations upon the scale-pattern of a group of mammals. Such generalisations would appear to be often unjustified for the following reasons: In many instances they are based first upon an insufficient number of observations along the length of each fibre, and secondly upon a technique of preparing the fibres for examination which would seem to be inadequate for accurate vision of all the delicate lines marking the boundaries of the scales. Although notable attempts to indicate these boundaries have been made (Hausman, 1920; Glaister, 1931), in the authors' opinion the results have not been satisfactory. Moreover, until Manby's methods, described in previous papers and also in this account, were perfected, there has been no really satisfactory method of photographing cuticular-scale patterns accurately.

Following the discovery of well-preserved fossil plants at Weak Law, North Berwick (Gordon, 1935, p. 280), a search of all the volcanic ashes in the neighbourhood was undertaken and special attention was given to those localities from which plant-remains had been recorded in the past. Isolated specimens had been from time to time discovered, but were usually of an unsatisfactory character—mostly fragments of charred wood such as frequently occur in volcanic ashes. More satisfactory specimens were found by Mr James Whitecross of North Berwick, and were recorded by the late Mr T. Cuthbert Day (Day, 1928, p. 48), from a thin bed of limestone in the ashes of Gin Head, Tantallon, and elsewhere in the vicinity.

The study of differential fertility in Great Britain in relation to the continued decline in fertility has been hampered by lack of adequate birth registration. Though the defect has now been partially remedied by The Population (Statistics) Bill, the study of past changes is still difficult. In a previous memoir (Charles and Moshinsky, 1938) the writer gave an analysis of regional fertility differences in England and Wales from 1911 to 1931. Gross reproduction rates were used as measures of fertility. In the present communication the same method is applied to changes in fertility in Scotland.

Descriptions of the two Coal Measure plants Senftenbergia and Dactylotheca have appeared in the literature on numerous occasions previous to this account. The former genus was first described by Corda (1845), and the latter by Zeiller (1883). Other contributions have been made by more recent investigators, and these have since been revised and supplemented by Kidston (1924). In each case the account was based upon an examination of the material as it appeared on the rock in the form of a compression. More recently, however, newer methods for dealing with plant compressions have been devised, and it was felt that the application of an improved technique would furnish a more adequate description of the plants, particularly of their fruiting members.

In 1858 C. H. Pander described as Ptydodus a number of teeth from Upper Devonian limestones in Russia. His admirable figures of complete teeth and of sections through them established the very chimæroid structure of these bodies. Since that time similar teeth have been repeatedly described, and have served for the establishment of three genera and many species from rocks of Middle and Upper Devonian age.

The Mucorales have a wide geographical distribution and for seventy years they have been the subject of investigation both in Europe and in America. In this country, however,little research has been done on this group, the only workers being Bayliss-Elliott (1930) who has investigated the microflora of the Dovey salt marshes, Dale (1912, 1914) who examined the fungus flora of soil at Cambridge, and Brierley (1923, 1927, 1928) who has done considerable work on soil study. Although certain of the Mucorales were isolated by the last named, he was mostly concerned with the general methods of soil culture. The important quantitative technique was devised by Brierley (1927). Oudemans and Koning (1902) were the first to show the presence of Mucors in the soil. They examined the soil fungi in Holland and isolated two new species of Mucors. Möller (1903) investigated the fungi found in Pine mycorrhiza and obtained a further four new species. Hagem (1907, 1910) studied the morphology and physiology of seventeen Mucors from the soil of Norway, seven of which were new species. In 1908 Lendner published his “Les Mucorinées de la Suisse,” an important contribution to the study of this group of fungi. A criticism which might be levelled at this work is that it is difficult to ascertain from it whether or not Lendner used pure cultures on which to base his descriptions. He merely states that “dilution methods used in Bacteriology were employed,” no mention of monospore cultures being made. Further important work on this group has been done by Korpatschewska (1909), Namy-slowski (1906, 1920), Naumov (1914, 1924, 1935), Ling-Young (1930), Johann (1932), Jensen (1912, 1931), and in the Kryptogamenflora der Mark Brandenburg (1935) Zycha gives a complete revision of the classification of the Mucorales. A survey of the geographical distribution of this group of fungi is found in the work of Niethammer (1935), while further classification has been done by Linnemann (1936). In America, Povah (1917) and Waksman(1916, 1917, 1922, 1927) have both added considerably to our knowledge of the Mucorales in the soil.

Nearly sixty years ago fossil fishes were first discovered at Glencartholm, since when so much material has been collected from this locality that very few museums in the British Isles are without some representative of this remarkable fauna; remarkable both for the number of specimens collected and for the variety of forms it contains. One of us (J. A. M.-T.) became interested in this fauna while studying some of its more problematical members, and spent a few weeks collecting at Glencartholm during the summers of 1933, 1934, 1935 and 1936. During these visits a large quantity of new material was amassed which, when studied by modern methods with a low-powered binocular microscope under liquids, particularly xylol, revealed far more of the anatomy than it had been possible for earlier workers to describe. Some of these results have already been published and the present paper deals only with the Actinopterygians. The new descriptions in this work are not intended to be exhaustive accounts of all that is known of these fishes, but merely to serve as a supplement and summary to the excellent descriptions of Traquair. In so doing an attempt has been made to re-define all the genera and species, and in some cases it has been necessary to repeat the existing description, but where this has been done care has been taken to be as brief as possible. The definitions of the genera are only intended to apply to the species here described, and are consequently confined to characters which are determinable in these species. In certain cases species have been found to exist on brief and inadequate descriptions, in two species the type specimens being unfigured; in these cases the types have been figured, and new and more complete accounts given. Where the shape or ornament of a bone was indeterminable, it has been omitted without comment, in order to make the text as short as possible.

Precise information about the food of the brown trout is somewhat scanty, especially as regards the relation existing between diet and environmental fauna.

(a) Day (1887) points out that “food which (brown) trout consume is of various descriptions. … They do not object to little fish, as the minnow, loach, sticklebacks, etc., water rats, young birds, frogs, snails, slugs, worms, leeches, maggots, flies, beetles, moths, waterspiders and even a lizard.” He concluded that the “tastes of some differ from those of their companions.”

The material to be described here was taken from individuals of a school of Pseudorca crassidens, forty-one of which were stranded at Buddon Ness in the estuary of the Tay in November 1935. There is very little published work on this species beyond reports on the occurrence of stranded individuals. Beebe (1924) refers to six skeletons found on the shores of the Galapagos Archipelago, and West (1935) gave a preliminary account of a male fœtus taken from a female stranded in Wales. More recently, Peacock, Comrie, and Greenshields (1936) gave an account of the Tay specimens, while Fraser (1936) published a review of various strandings around our British coasts, and Gill (1935) has dealt with those stranded in South Africa (see abstract in Nature, September 1936). With regard to the reproductive system valuable assistance has been obtained from recent researches on other species by MacIntosh and Wheeler (1929), Wheeler (1930), Ommanney (1932), and Laurie (1937), published in Discovery Reports, while earlier papers, also on other species, by Schulte (1916) and Meek (1918) have also been consulted.