The fossiliferous bed in the Upper Comley Sandstone, described by Cobbold & Pocock (in 1934) as the ‘Paradoxides forchhammeri Grit’ and correlated by them with the Andrarum Limestone of the late Middle Cambrian (P. forchhammeri Stage) in Scandinavia, is shown to be a shallow-water development of the older punctuosus Zone (medial Middle Cambrian, P. paradoxissimus Stage). It is here re-named the ‘Rushton Brook Bed’. The trilobite fauna, formerly considered comparable with that of the Andrarum Limestone, is reviewed and found taxonomically distinct, the supposed similarities being attributable to facial and preservational factors.

We are never more disposed to give credit to a philosophical system, than when we meet with a case of its successful application, unknown to the author, or containing circumstances which he had not taken into account when he formed that system.

The facts brought forward in the following paper, which, according to my view of the subject, clearly indicate the operation of immense torrents, can be accounted for, I think, in a very satisfactory manner, by the Huttonian Theory, and consequently afford some very powerful arguments in support of it.

Chemostratigraphical correlation provides valuable insights into the status of the Colonsay Group, which field and structural studies have left unresolved. Using published discriminant functions, major and trace element data support previously proposed correlations of the Colonsay Limestone with Appin Group (Lower Dalradian) limestones, and particularly with the Ballachulish Limestone Formation. They also tend to preclude correlations with other nearby Dalradian carbonate formations, with marbles of the early Precambrian Lewisian complex, and with miscellaneous unassigned limestones in a similar structural position to the Colonsay Limestone, astride the Great Glen fault.

The present part of this memoir contains descriptions of four additional specimens of Osmundites which have been obtained from various sources.

We are indebted to Dr G. Nathorst for the material of Osmundites spetsbergensis, Nathorst MS., which was first collected by Dr G. Nordenskiöld on the Spitzbergen Expedition of 1890 at Nordenskiöldsberg, and subsequently by Dr B. Högbom in 1910 at Van-Mijensberg, Spitzbergen.

Our thanks are also due to Dr A. Rothpletz, Director of the Geologisch-palaeontologische Staatssammlung, München, for kindly placing in our hands the type specimen of Osmundites Carnieri, Schuster, for investigation and redescription.

The observations which were made in Loch Earn during August 1911 and described in the Trans. Roy. Soc. Edin., vol. xlviii, p. 629, demonstrated that in that loch there was during autumn a fairly definite temperature or density discontinuity, and suggested that the loch was a peculiarly suitable one in which to observe in greater detail the boundary waves occurring at the discontinuity. The previous investigation had for its main purpose the demonstration of the existence of standing oscillations at the discontinuity, and in that was entirely successful. The observations showed, however, that in addition to the primary standing oscillations there were other less regular movements about which the observations gave little information, as they were not made at sufficiently close intervals of time.

1. A year ago last April, Prof. Tait proposed that I should undertake to derive from Mr Kirkman's polyhedral drawings the alternate ± knots of eleven crossings, thus doing for order 11 what had been done so admirably by himself in orders 8, 9, and 10.

2. The work has been a very protracted one, because of the great number of forms involved—more than three times as many as in all preceding orders combined. Mr Kirkman's manuscript contains 1581 forms, of which 22 are bifilar and 16 duplicates. I find from the remainder 357 knots with 1595 forms as shown in the following table:—

As this is an odd order, perversion doubles these numbers, making 714 elevenfold knots, with crossings alternately over and under.

3. It has been thought unnecessary to show upon the Plates more than one form of each knot; all, however, have been drawn. Knots of each class having the same number of forms are grouped together to make more simple the identification of a particular elevenfold. A small figure following the series number upon the plates indicates how many distinct forms each knot can assume. Knots 84, 357, and 2386 are misplaced.

Protoclepsydropsis kidstoni (Bertrand) Hirmer is a small fossil fern with a slender stem about 3 mm. diameter bearing petioles of a Clepsydropsis type in a ⅖ phyllotaxy.

Larger isolated Clepsydropsis petioles from the same rocks probably belong to a larger related plant. In these the petiolar bundle is sometimes oval in cross section with protoxylem groups nearer one tangential surface. Occasionally roots are borne on these petioles. A resemblance to the petioles of Asterochlœna laxa Stenzel is pointed out.

1. To complete the census of knots of any given order, that is, minimum number of crossings, it is necessary to include not only those in which the crossings are taken alternately over and under (Alternate ±), but also the Non-Alternate ±, those in which two or more consecutive crossings are alike over or alike under. Professor Tait has figured the forms of the alternate ± knots, of orders three to nine inclusive, on Pl. XLIV. vol. xxxii., Trans. Roy. Soc. Edin.; the object of this paper is to describe the non-alternate knots of these orders.

Depuis la publication de mon mémoire sur les Spongiaires de V Expedition antarctique nationale écossaise (9), j'ai reçu de M. le Dr. W. S. Bruce quelques Eponges antarctiques faisant aussi partie des collections de la Scotia mais dont le triage s'était trouve retardé.

Indépendamment de fragments en double d'espèces mentionées dans mon mémoire, ce second lot contenait plusieurs formes qu'il me paraît utile de signaler ou de décrire.

The former paper (5) on the Anatomy of Cephalodiscus was incomplete in certain particulars, which I am now in a position to add. These are mainly in regard to the alimentary canal, the nervous system, and the reproductive organs. To the present description of these will be appended an account of the budding processes, which are a very conspicuous feature of the species.

Proximal braided stream deposits of the Old Red Sandstone of central Scotland are characterised by a variety of upward coarsening units formed during downstream migration gravel bars. Transitional variations in thickness, grain size and structure of these units, and their associated sediments are used to establish facies and paths of facies change (lineages). Three facies lineages are recognised which are interpreted as recording the downstream changes the structure of sediments of three different types of braided river systems. Lineages differ from each other in proportion of sandstone, channel depth and the structure of upward coarsening units: lineage 1 represents alluvium formed in a river system which produced texturally mature gravels and which increased in depth downstream; lineage 2 comprises sediments deposited in shallow channels which become shallower downstream; lineage 3 represents a downstream change from conglomerate to sandstone and from an unchannelled to achannelled regime.

Stream depth and ratio of sand to gravel exert fundamental controls on the structure of alluvium. Thick (thickness >50 m) sections showing vertical changes in clast size often comprise single facies lineage. Thick upward coarsening sequences are found with lineages 2 or 3 and upward fining with lineage 1 or 3.

A necessary preliminary to the study of the complex problems involved in the biology of lakes is to ascertain the facts. The collection of the bathymetrical data was begun many years ago by Sir John Murray and Mr Pullar, and is nearing completion under the Lake Survey. The next thing is to take a census of the inhabitants. This we are now trying to do by compiling lists of the animals and plants living in the lakes. The study of the problems after the data are collected falls outside the province of a lake survey, and within that of some permanent biological station. This present compilation is one step in the accumulation of the facts.

Conglomerates from the Lettergesh Formation in the Silurian sequence of N Galway, Ireland, demonstrate palaeocurrents from the NE. Fabric studies demonstrate that the conglomerates were emplaced largely by traction currents and not by down-slope sliding or dispersive currents. Stratigraphic relationships demonstrate that the conglomerates were deposited in an environment which was adjacent to fluviatile, shallow-marine and deeper shelf facies at different times. A fan-delta environment of deposition is suggested, which requires a modification of previous Silurian sea-level curves at, or near, the base of the Wenlock.

I have to apologise for placing this communication before you in a somewhat incomplete form. My work has been much interrupted in the past, and it will again shortly be stopped for a considerable time. I have therefore decided to place before you the results so far as they are worked out.

In an experimental inquiry into the action of water on lead, published by me in 1829, in continuation of some previous researches by Guyton-Morveau, it was stated as the general result, that all very pure waters, such as distilled water, rain, and melted snow, act upon lead,—dissolving a trace of it, and causing the formation of an insoluble carbonate of lead in large quantity. It was like-wise shewn, that this action is prevented by the existence of neutral salts in solution; so that most terrestrial waters, as they contain saline matter, act feebly and only in circumstances favourable in other respects. Farther, it appeared to flow from comparative experiments, that this preventive power depends upon the acids of the salts, and not upon their bases;—and that their energy as preventives, that is, the minuteness of the proportion required to annihilate the action, is in the ratio of the insolubility of the compounds which the acids of the salts are capable of forming with oxide of lead.

The lavas of the Bathgate and Linlithgow Hills occur, as already described, in a series of zones alternating with sedimentary deposits. So far as their field characters are concerned they may be grouped with convenience into two classes: fine-grained, columnar, basaltic types, usually porphyritic with augite and olivine, rarely with felspar, and coarser-grained, doleritic types, usually much decomposed, not evidently porphyritic or porphyritic with olivine alone. The yellow crusts of the compact lavas are minutely vesicular and pumiceous, while steam-cavities are rare in the interior. The doleritic lavas on the other hand are coarsely vesicular and amygdaloidal above and below, and frequently also throughout. The blue basaltic types are relatively very fresh; the doleritic types are frequently entirely decomposed into a whitish, earthy material, with knots of limonite, calcite, and quartz, similar in many respects to the white trap of the coal-fields. Good examples of this mode of weathering may be found in the Riccarton Burn. The differences in texture are probably to be referred not so much to differences in chemical composition as to the effect of variation in the quantity of water vapour contained in the successive flows. The coarse and open structure of the dolerites has evidently also given freer scope to the action of decomposing influences than the more compact structure of the basalts. Both types are much veined by such secondary minerals as calcite, siderite, limonite, quartz, chalcedony, and various zeolites. Frequently cavities in the veins, steam-holes in the pumiceous crusts, and even vesicles within the solid rocks, are found filled with brown viscous pitch or black lustrous asphalt. Such occurrences undoubtedly indicate that these rocks have been subjected to some slight extent to post-volcanic pneumatolytic action.

The Cephalopoda collected by the Scotia may, with a few trifling exceptions, be separated geographically into three divisions, coming respectively from South Africa, South America, and the Antarctic.

The holotype and only known specimen of Rhachiosteus pterygiatus Gross is partially redescribed and new restorations are given. Attention is drawn to important points in its osteology and the possible development of a cutaneous sensory system. A definition of the family Rhachiosteidsæ Stensiö is given. This family differs from all other described groups of euarthrodires in the lack of posterior lateral and posterior dorsolateral flank plates. Rhachiosteus is a pachyosteomorph brachythoracid, as defined in the text, and may be fairly closely related in some way to the (coccosteomorph) family Coccosteidsæ. There is no indication that it is closely related to any other known pachyosteomorph, or to other groups of arthrodires, such as the Rhenanida and Ptyctodontida, in which there are no posterior flank plates.

Four kinds of robust elements have been recognised in Amorphognathus quinquiradiatus Moskalenko, 1977 (in Kanygin et al. 1977) from the early Late Ordovician of Siberia, indicating that at least 17 elements were present in the apparatus, one of them similar to the P1 element of the Early Silurian Distomodus. The new generic name Moskalenkodus is proposed for these conodonts with a pterospathodontid-like S series element morphology. This implies that the related Distomodus, Pterospathodus and Gamachignathus lineages had a long cryptic evolutionary history, probably ranging back to the early Ordovician, when they split from the lineage of Icriodella, having a duplicated M location in common. The balognathid Promissum, with a 19-element apparatus, may have shared ancestry with Icriodella in Ordovician high latitudes, with Sagittodontina, Lenodus, Trapezognathus and Phragmodus as possible connecting links. The pattern of the unbalanced contribution of Baltoniodus element types to samples suggests that duplication of M and P2 series elements may have been an early event in the evolution of balognathids. The proposed scenario implies a profound transformation of the mouth region in the evolution of conodonts. The probable original state was a chaetognath-like arrangement of coniform elements; all paired and of relatively uniform morphology. This was modified at the origin of protopanderodontids by the introduction of a medial S0 element, which resulted in the separation of the exposed unit of M and S series elements from the P series elements hidden in the throat. A rotation of the S series elements to an almost horizontal position in early prioniodontids may have promoted duplication of the M element pair. In Gamachignathus, Icriodella and Pterospathodus lineages, these elements are differentiated morphologically. Subsequent anteriorward bending of the P element series caused duplication of the balognathid P2 element pair, but they remained undifferentiated, even in the otherwise elaborate Promissum. The whole clade of conodonts with supernumerary element pairs in the apparatus has its roots in high latitudes of the Ordovician.