The subject of the present memoir occupies a distinguished position as lecturer and teacher of our science in the University of Cambridge, one which he has held for more than thirty years, and he is well known among geologists generally as a high authority on the Palæozoic rocks, his writings being recorded in the “Quarterly Journal” of the Geological Society (of which Society he has filled the offices both of Secretary and President). His name has also frequently appeared as the author of important papers in the GeologicalMagazink and other works.