LIST OF ILLUSTRATIONS 
PLATE 
I, THE SHELL (IN SECTION) AND ANIMAL OF THE 
PEARLY Navticus (Nautilus pompilius). 
II. Various GaAsTROPODS, SHOWING THE ANIMALS 
CRAWLING, 
TIT. DiaGRAMMaTIC SKETCHES OF THE STRUCTURE OF THE 
GILLs AND Nervous SysTEM OF MOLLUscA. 
DRAWINGS OF THE DIFFERENT FORMS OF THE 
MANDIBLES AND RADULA OF MOLLUSGCA, ETC, 
IV. DiacramMatic SKETCHES TO ILLUSTRATE (a) THE 
TORSION OF THE GastTROPOD Bopy, (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 Nazica, 
VII. NoTcHED AND PERFORATED GASTROPOD SHELLS. 
SHELL STRUCTURE AND REMOVAL OF PoRTIONS OF 
THE SHELL, 
VIII, Various DervicEs For ExcLuDING ENEMIES FROM 
GastROPoD SHELLS, 
IX. Various Forms oF SHELL AND ANIMAL IN THE 
(4) PotypLacorHora, (B) APLACOPHORA, AND (C) 
PROSOBRANCHIA (DOCOGLOSSA AND RHIPIDOGLOsSA), 
ix 
