Sub-Kingdom VI. MOLLUSCA:' 
(Malacozoa, Blainville ; Saccata, Hyatt.) 
THE Mollusca form a well-characterised, and, on the whole, remarkably 
homogeneous group of Invertebrates, which have existed since the earliest 
recognised advent of life upon the globe. Their progressive modifications 
afford us a most important guide to the successive stages of the evolution of 
organic life as preserved in the various geological horizons. 
The Mollusca are characterised as a group by passing through a Trocho- 
sphere and a Veliger larval stage; by possessing bilaterally symmetrical, 
unsegmented bodies ; a larval shell gland, from which a harder exoskeleton 
or shell is secreted, though not always permanently retained; a mouth, 
1 Literature : 
Adams, H, and A., The Genera of Recent Mollusca, 2 vols. London, 1853-58. 
Philippi, R. A., Handbuch der Conchyliologie. Halle, 1853. 
Keferstein, W., Die Malacozoa (Bronn’s Classen und Ordnungen des Thierreichs, Bd. III.), 1862-66. 
Tryon, G. W., and Pilsbry, H. A., Manual of Conchology, 16 vols. Philadelphia, 1879-96. 
Fischer, P., Manuel de Conchyliologie et de Paléontologie conchyliologique, 1880-87. 
Woodward, S. P., Manual of the Mollusea. 4th Edition, with Appendix by R. Tate, 1880. 
Tryon, G. W., Structural and Systematic Conchology, 3 vols. Philadelphia, 1882-84. 
Lankester, £. R., Encyclopaedia Britannica, Article Mollusca, 1883 
Ihering, H. von, Le systeme naturel des Mollusques (Bull. Sci. de la France, XXIII.), 1891. 
Pelseneer, P., Introduction a Vétude des Mollusques. Brussels, 1894. 
Sowerby, J., Mineral Conchology of Great Britain, 7 vols. London, 1812-30. 
Brocchi, G. B., Conchiologia fossile subappenina, 2 vols. Milan, 1814. 
Deshayes, G. P., Coquilles fossiles des environs de Paris, 3 vols., 1824-37. 
Goldfuss, A., Petrefacta Germaniae, 1826-40. 
Conrad, T. A., Fossil Shells of the Tertiary Formations of North America (1832-33); and Fossils 
of the Medial Tertiary of the United States (1838-61). Reprints 1893. 
Morton, S. G., Synopsis of the Organic Remains of the Cretaceous Group of the United States, 1834. 
Philippi, R. A., Enumeratio Molluscorum Siciliae, 2 vols., 1836-44. 
Groteloup, J. P. S., Catalogue zoologique du Bassin de Gironde. Bordeaux, 1838-40. 
Hall, J,, Palaeontology of New York, vols. I.-VIII. Albany, 1847-95. 
Wood, S., Monograph of the Crag Mollusca (Palaeont. Soe. vols. I.-II.), 1848-56. 
Sandberger, G. and F., Die Versteinerungen des Rheinischen Schichtensystems in Nassau, 1850-56." 
Morris and Lycett, Monograph of the Mollusea of the Great Oolite (Palaeont. Soc.), 1850-63. 
M‘Coy, F., British Palaeozoic Fossils. London, 1851-55. 
Pictet and Campiche, Description des Fossiles du terrain cretacé de Ste. Croix (Palaeont. Suisse, ser. 
V., vols. I.-IV.), 1858-71. 
Quenstedt, F. A., Der Jura. Tiibingen, 1858. 
Sandberger, F., Die Conchylien des Mainzer Beckens. Wiesbaden, 1860-63. 
Deshayes, G. P., Description des animaux sans verttbres decouverts dans le Bassin de Paris, 5 vols. 
Paris, 1860-66, 
Loriol, P. de, Monographs of the Fauna of the Upper Jura of Switzerland, Haute-Marne, Yonne, 
Boulogne-sur- Mer, Valtin, Tonnerre ; of the Neocomian of Mt. Saleve; the Urgonian of 
Landeron ; the Gault of Cosne, ete., 1861-75. 
