PLATE I 



PLATE I 



The Pearly Nautilus (Nautilus pompilius, Linn., after Owen). The 

 chambered shell has been laid open down to the central plane. 



a. The mantle. 



b. The dorsal fold of the 



mantle. 

 e. Nidamental gland. 



g. Shell muscle. 

 i, i, i. Shell siphuncle. 

 k. Funnel. 



n. Hood 

 o, o, o. Pedal lobes. 

 p. Tentacles, 

 s. Eye. 

 x, x. Septa. 



z. Body chamber. 



Frontispiece 



