LIST OF ILLUSTRATIONS 



PLATE 



I. The Shell (in Section) and Animal of the 

 Pearly Nautilus (Nautilus pompilius). 



II. Various Gastropods, showing the Animals 

 Crawling. 



III. Diagrammatic Sketches of the Structure of the 

 Gills and Nervous System of Mollusca. 

 Drawings of the Different Forms of the 

 Mandibles and Radula of Mollusca, etc. 



IV. Diagrammatic Sketches to Illustrate (a) The 

 Torsion of the Gastropod Body, (b) The Tran- 

 sition from a Flat-Coiled Gastropod Shell to 

 a Right- or a Left-Handed Spiral One, (c) The 

 Mantle Openings in Bivalves, and (d) The 

 Different Forms of Gills in Bivalves. 



V. Different Forms of Coiling, of Aperture, and 

 Ornamentation in Gastropod Shells. 



VI. Topography of Gastropod Shells, and Formation 

 of Callus in the Umbilicus of Natica. 



VII. Notched and Perforated Gastropod Shells. 



Shell Structure and Removal of Portions of 

 the Shell. 



VIII. Various Devices for Excluding Enemies from 

 Gastropod Shells. 



IX. Various Forms of Shell and Animal in the 

 (A) Polyplacophora, (B) Aplacophora, and (C) 

 Prosobranchia (Docoglossa and Rhipidoglossa). 



