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CONTENTS 
PAGE 
Introduction 1 
Topography and drainage 2 
Areal distribution of Silurian dolomite 5 
Stratigraphy and faunas 6 
Description of species 13 
ILLUSTRATIONS 
Plate I. Leptaena sinuosus n. sp 19 
u II. Conchidium decussatus Whiteaves 21 
u III. Conchidium decussatus Whiteaves 23 
“ IV. Conchidium decussatus Whiteaves 25 
