The generally accepted interpretation of the structure of the Southern Uplands has been that of an anticlinorium to the north-west flanked by a synclinorium to the south-east. This structure, however, has always been illustrated as one large anticlinorium since the Hawick rocks in the core of the synclinorium have been considered to be older than the Riccarton (Wenlockian) Beds which lie to the south. In Kirkcudbrightshire, a reverse age relationship is demonstrated with the result that the beds could in fact form the southern limb of the synclinorium. When this is shown to be the case doubts are thrown on the validity of the fold and two alternative interpretations are given.

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New sedimentary structures are described from a thick greywacke/ mudstone succession. The structures include modified ripple marks, nodule trails and orthocone prod marks. Further evidence is given and comment made on the genesis of longitudinal ridges, chevron marks and large-scale current bedding. Palaeocurrent directions statistically determined from 353 observations show that the dominant turbidity currents during Riccarton (Wenlock) and Upper (?) Silurian times came from the north-east (i.c. parallel to the axis of the Caledonian geosyncline) with minor currents from the south-west. Currents at right angles to the axis of the geosyncline deposited the transverse ripples. CONTENTS

The ecology of living lingulids is reviewed. Occurrences are noted of fossil shells of Lingula lying vertically, with their anterior ends upper most, to the bedding-planes of various sediments. These shells are considered to be in the burrowing position adopted by the animals during life. In the Top Hosie Shale, Kilsyth, there is a palaeoecological association of burrowing animals, vertical shells of Lingula squamiformis being associated with shells of the burrowing lamellibranchs, Nuculopsis gibbosa and Sanguinolites costellatus. Two shells of L. squamiformis from this horizon show what is probably the pyritized infilling of the pedicle tube. The mode of life of fossil Lingulae is considered to have been substantially the same as that of living lingulids.