PLATE I. 



Fig. 1. — A Nautilius seen from the right side, the right half of the shell having been cut away. 

 AV, anterior ventral aponeurotic band. 

 ( ', cirrus of a digital tentacle. 



Csh, cephalic sheath, composed of the fused sheaths of digital tentacles. 

 CR, erus of funnel. 

 DM, dorsal portion of mantle. 



E, eye 



F, funnel. 

 Ho, In Hid. 



T, involution of shell. 



(>', preocular tentacle. 



' • postocular tentacle. 



I'V, posterior ventral aponeurotic band. 



S, living chamber of shell. 



Si, siphon <>f shell. 



SI, siphuncle of body. 



SM, area of attachment of shell muscle. 



Sp, lai t I'm med septum. 



VM, ventral portion of mantle. This is free from the body from the edge as far hack as the anterior ventral 



aponeurotic hand. 



pis 



