The field relations and petrography of a number of small rock bodies occurring near Rockcliffe at the southern margin of the Criffell-Dalbeattie granodiorite are described. The evidence suggests that they were formed by the metasomatic replacement of greywacke and shale hornfelses by Na-bearing and later K-bearing solutions which preceded the ascending granodiorite magma. This metasomatic transformation brought about the development of two distinctive rock types. Equigranular quartz-dioritic rocks which generally grade into the hornfelses are regarded as the result of static metasomatic replacement of the hornfelses with no appreciable movement of the permeated rock. In contrast, rocks of similar mineralogy but occurring as sharply bounded bodies with a conspicuous porphyroblastic texture, are thought to have attained their characteristic features by a certain amount of metasomatic mobilization of the permeated material. Because of the intrusive appearance of these porphyroblastic rocks and their occurrence near the margin of the granodiorite pluton they are here referred to as “marginal porphyrites”.

On Ord Ban, quartzite in superposed recumbent folds trending north–south is separated by a slide from mica-schist, granulite, and marble folded in monoclines trending east–west. The reasons for distinguishing between these two styles of folding are given, and the characters of the two styles are contrasted. A fold in quartzite and a fold in marble are described in detail, and kinematic interpretations are attempted. It is concluded that evidence of an early deformation involving mylonitization has been preserved in the quartzite, and that the latest tectonic event distinguishable was the production of the monoclines with attendant twinning of calcite and dolomite.

The morphology of Cyrtograptus rigidus Tullberg n. subsp. A is described from uncompressed material. Particular attention is directed to the sequence of development of the connecting structure of cladium and main branch, which is demonstrated with the aid of figured growth stages of cleared and uncleared specimens. Also discussed is the intimate relationship of relative rate of growth of characters of cladium to those on the main branch. Cursory study of numerous other uncompressed species of Cyrtograptus in the author's collection reveals that the principles of cladial development outlined here are of general application.

The extinct Ratnapura fauna of Ceylon is a radiation from the Indian Shivalik. In it occur a hexaprotodont hippopotamus and a race of Elephas maximus which is the most recent member of the Proboscidea. Since such an association is unknown elsewhere, it has given rise to many explanatory theories. A uranium test of associated fossils of both animals now establishes that this has resulted from redeposition and that the animals were not contemporaneous. This makes less vague the hitherto conjectural views regarding the earth movements, and the ages of the gem deposits and of the early human lithic artefacts in them.

Deformation of plastic kaolinite-illite clay caused alignment of authigenic prisms of rutile and tourmaline on surfaces produced by parallelism of the basal pinacoids of the clay-minerals. An a–lineation appeared in the outer layers of an extruded cylinder but a b–lineation in those of a cylinder formed by rolling. A Wineation occurred at the periphery of a circular disc made by spreading. Localized tensional failures, cognate with ac joints, accompanied the b–lineations which were in directions of elongation. The orienting movements were thought to occur in the water-films separating the clay-flakes, but the mechanisms which produce a– and b–lineations are presumably identical. Thus it can be argued that the a–lineation also follows a direction of elongation.

An area of rocks in S.E. Co. Wexford, the age of which has not been previously established, is now shown to be a metamorphic assemblage, probably of Pre-Cambrian age. It is suggested that this formed the south-western extension of the L. Palaeozoic Irish Sea geanticline postulated by previous workers.

In the Clashnessie district the original or Scourian complex is represented chiefly by hornblendic gneisses and shows simultaneous close folding on 55°–235° (A 1) and 155° (A 2) axes. The general disposition of the formations is largely related to open folding on the A 1 axis.

The effects of later movements, post-dating the basic dykes, are comparatively slight, but are shown by the sporadic development of a schistosity and a lineation, which plunges to the south-east, together with occasional sharp folds at about 207° (A 3) and 114° (A 4).