Those who have carefully studied the crystalline schists cannot fail to have noticed that a community of structure—a sort of family likeness—prevails throughout any one group of rocks, while those which occur apparently at different horizons exhibit dissimilar structures. Thus the marbles associated with any group of crystalline schists are coarse or fine in grain, according to the structure of the latter. But to this rule exceptions appear, at first sight, not infrequent. For instance, in the Alps, we find not uncommonly, in that group of schists which seems to occupy the highest position, marbles which present an abnormally compact aspect. On closer examination they prove indeed to be crystalline in structure, but the crystals seem so small, the general structure so compact, that until we find them graduating into typical mica or other schists, we can hardly feel satisfied we are not being duped by infolded limestones of Mesozoic or Palæozoic age.

Kames, åsar, and minor topographical features.—Kames and åsar are usually found associated. Indeed, the one class of elevations shades into the other so gradually that it is sometimes impossible to draw the line between them. Though the kames may occur singly, they are often in ranges of several, perhaps extending for miles. Each is usually elliptical in outline, and its longer axis corresponds in direction with the range. The åsar are frequently intercepted by channels of erosion, by which they are divided into ranges of oblong hills, the direction of which is very nearly the same as that of the kames proper. In Dubuque county, Iowa, where these features have been most thoroughly studied, this direction is about S. 75° E. Within 40 miles south-west from there the direction changes to abut S. 45° E., and in the next 50 miles the direction becomes a trifle west of south; and this is the general direction over the greater part of the region examined.

Sp. Chars.—Tooth bidentioulated with a re-entering angle between the denticles; sides sloping down to the lateral angles; anterior profile convex; posterior profile concave. The most prominent portion of the anterior surface is at the centre of the inferior margin of the crown, where it becomes bowed-out, whence the surface gradually recedes to the cutting edge of the crown on the one hand, and more rapidly towards the root on the other.

Knowledge about marine reptile diversity and disparity during the Late Jurassic is increasing. This contribution describes marine reptile skeletal elements (ichthyosaur and plesiosaur) from Kingofjeld mountain in NE Greenland. The assemblage is early Late Oxfordian (Late Jurassic) in age, and consists of c. 100 disarticulated skeletal elements. The location is of biogeographic importance as it was at the time situated between the Boreal realm and the Tethys Sea and is promising in terms of future prospecting.

The question of the origin of the Archæan rocks is one of such great interest that it will not be thought unimportant on the one hand to record any facts that may bear upon it, and on the other to examine somewhat severely all the evidence that may be from time to time brought forward on the subject. Among the facts which may be adduced in support of the view that the Archæan rocks are altered sedimentary strata, the occurrence of breccias and conglomerates may well claim a foremost place; and a vast amount of superincumbent theory must rest on a very shaky foundation if there be any doubt whether some of those ancient fragmental beds be true conglomerates or not. The manner of occurrence, the mode of formation, and the character of pseudo-breccias and pseudoconglomerates become therefore questions of first importance.

On the 24th of June, 1885, a paper by me, entitled “Observations on some imperfectly known Madreporaria from the Cretaceous Formation of England,” was read at a meeting of the Geological Society which, encountering an adverse report from the referee, was with the consent of the Council, withdrawn by me, and published verbatim in the Geological Magazine of the same year (Dec. III, Vol. II, pp. 541–563, PI. XIV), 1885. The present communication is a continuation as well as a correction of the former one, which has become necessary from the acquisition of additional material.

Leidleite and Inninmorite.—Typical rocks of these groups are as yet unknown in the Clyde area. A N.N.W. dyke at Barrassie Sands, near Troon (Ayrshire), has points in common with leidleite. It shows anorthite phenocrysts in a subvariolitic groundmass of acicular felspar and augite, enveloped in a partially devitrified glassy base. A north–south dyke at the north end of Loch Fad, Bute, may perhaps be regarded as a doleritic end-variety of leidleite (see Anderson & Radley, 1916, fig. 2b, p. 208). A pitchstone-like dyke from the Smurig Burn in the south of Arran has all the characters of leidleite, except that it carries rather abundant granular augite, instead of acicular crystals.