(1) 'Geology of Oxford and the Thames Valley.' Phillips. (2) 'Geology of Yorkshire,' vol. ii. Phillips. (3) 'Memoirs of the Geological Survey of Great Britain.' (4) 'Geology of Cheltenham.' Murchison, 2d ed. Buckman. (5) 'Introduction to the Monograph of the Oolitic Asteriadæ' (Palæontographical Society). Wright. (6) "Zone of Avicula contorta and the Lower Lias of the South of England"--'Quart. Journ. Geol. Soc.,' vol. xvi., 1860. Wright. (7) "Oolites of Northamptonshire"--'Quart. Journ. Geol. Soc.,' vols. Xxvi. and xxix. Sharp. (8) 'Manual of Geology.' Dana. (9) 'Der Jura.' Quenstedt. (10) 'Das Flötzgebirge Württembergs.' Quenstedt. (11) 'Jura Formation.' Oppel. (12) 'Paléontologie du Département de la Moselle.' Terquem. (13) 'Cours élémentaire de Paléontologie.' D'Orbigny. (14) 'Paléontologie Française.' D'Orbigny. (15) 'Fossil Echinodermata of the Oolitic Formation' (Palæontographical Society). Wright. (16) 'Brachiopoda of the Oolitic Formation' (Palæontographical Society). Davidson. (17) 'Mollusca of the Great Oolite' (Palæontographical Society). Morris and Lycett. (18) 'Monograph of the Fossil Trigoniæ' (Palæontographical Society). Lycett. (19) 'Corals of the Oolitic Formation' (Palæontographical Society). Edwards and Haime. (20) 'Supplement to the Corals of the Oolitic Formation' (Palæontographical Society). Martin Duncan. (21) 'Monograph of the Belemnitidæ' (Palæontographical Society). Phillips. (22) 'Structure of the Belemnitidæ' (Mem. Geol. Survey). Huxley. (23) 'Sur les Belemnites.' Blainville. (24) 'Cephalopoden.' Quenstedt. (25) 'Mineral Conchology.' Sowerby. (26) 'Jurassic Cephalopoda' (Palæontologica Indica). Waagen. (27) 'Manual of the Mollusca.' Woodward. (28) 'Petrefaktenkunde.' Schlotheim. (29) 'Bridgewater Treatise.' Buckland. (30) 'Versteinerungen des Oolithengebirges.' Roemer. (31) 'Catalogue of British Fossils.' Morris. (32) 'Catalogue of Fossils in the Museum of Practical Geology.' Etheridge. (33) 'Beiträge zur Petrefaktenkunde.' Münster. (34) 'Petrefacta Germaniæ.' Goldfuss. (35) 'Lethæa Rossica.' Eichwald. (36) 'Fossil Fishes' (Decades of the Geol. Survey). Sir Philip Egerton. (37) 'Manual of Palæontology.' Owen. (38) 'British Fossil Mammals and Birds.' Owen. (39) 'Monographs of the Fossil Reptiles of the Oolitic Formation' (Palæontographical Society). Owen. (40) 'Fossil Mammals of the Mesozoic Formations' (Palæontographical Society). Owen. (41) 'Catalogue of Ornithosauria.' Seeley. (42) "Classification of the Deinosauria"--'Quart. Journ. Geol. Soc.,' vol. xxvi., 1870. Huxley. CHAPTER XVII. THE CRETACEOUS PERIOD. The next series of rocks in ascending order is the great and important series of the Cretaceous Rocks, so called from the general occurrence in the system of chalk (Lat. _creta_, chalk). As developed in Britain and Europe generally, the following leading subdivisions may be recognised in the Cretaceous series:--