ee Cr 
SR TT P* * 
: eee: a 
— roe 
181 
of the animal. We have here likewise to note the position of 
the tentacules and the place of the hood, which may probably 
be the homologue of the Aptychus. The septa are likewise 
seen to be concave towards the aperture, and convex towards 
the spire of the shell, and they all are perforated at the centre 
by the siphuncular tube, which proceeds from the posterior side 
of the Cephalopod to traverse the septa up to the last air- 
chamber. 
Fic. 32.—Verticul section of the shell of Nautilus pompilius, showing the 
siphuncle and the situation of the animal in the last chamber. 
Fie. 33.—Nautilus wmblicatus, Fie. 34.—Section of the shell of 
Lam. Nautilus pompilius, Linn. 
In fig. 34 we have a vertical section of the Nautilus shell 
(fig. 33). The chamber in the section is seen to extend to one 
half of a whorl, and from the inner side of each septum we 
observe a short funnel-shaped process projecting backwards, 
which affords attachment to the membranous siphuncle seen 
