ON THE ANATOMY OF NAUTILUS POMPILIUS. 203 



ferent individuals, and in any one individual the right and left 

 margins present exactly the same appearance; there being 

 nothing to point to one in particular being kept habitually 

 folded over the other. From this, and from the general muscular 

 character of the funnel, I have little doubt that the living 

 animal possesses the power of unrolling and flattening it out, 

 possibly even of using its broad lower face to creep on or 

 adhere to rocks. In spirit-specimens one can readily so unroll 

 the funnel, and when this is done the appearance of the animal 

 is very striking, as is shown in PI. IX. fig. 1, where, by the way, 

 the mantle-flap has been partially removed so as to afford a 

 better view of the creature. One is here impressed, first of all, 

 by the sharp way in which the funnel is marked off from the 

 hood-tentacle-head mass. Everywhere a deep groove separates 

 them'. There is nothing here to suggest or even support the 

 view that part of the foot has grown up round and become 

 fused with the head. Again, the great size of the organ is very 

 impressive — more especially its width from side to side, — and 

 its entire condition is such as at once, to my mind irresistibly, 

 to suggest that in this organ one has the representative of the 

 whole of the foot of the ordinary Gasteropod. 



The general relations of the parts in Nautilus impress upon 

 one that : — 



(1) The hood-tentacle complex is preponderatingly an- 

 terior (dorsal) to the buccal mass, its posterior 

 (ventral) parts being relatively insignificant. 



(2) The hood-tentacle complex is most sharply marked 

 off from the funnel by a deep groove. 



(3) The funnel is enough, in itself, to represent the 

 whole of the Gasteropod foot. 



Considering merely them alone, there is no suggestion of 

 doubt that the hood-tentacle complex is cephalic; that the 

 funnel is the Gasteropod foot. 



1 In this connection the figure given by Lankester {Zoological Articles, fig. 

 91) seems scarcely in a«cord with the actual conditions as shewn in my 

 specimens. 



