ON THE PAGODA STONE OF THE CHINESE. 405 



top of the shell just out of the water, as observed 

 by Ruinphius. The shell was maintained with its 

 major plane in a vertical position, and its mouth 

 directed upwards. The animal seemed unable to 

 sink, and the floating of the shell, as described, 

 was due no doubt to some expansion of gas in 

 the interior, occasioned by diminished pressure. 

 The animal moved backwards slowly by a suc- 

 cession of small jerks, the propelling spouts from 

 the siphon being directed somewhat downwards, so 

 that the shell was rotated a little at each stroke 

 upon its axis, and a slightly greater area of it 

 raised above the surface of the water. Occasion- 

 ally, when the animal was frightened or touched, 

 it made a sort of dash by squirting out the water 

 from its siphon with more than usual violence, so 

 as to cause a strong eddy on the surface of the 

 water. On either side of the membranous, oper- 

 culum - like headfold, which when the animal is 

 retracted entirely closes the mouth of the shell, 

 the fold of the mantle closing the gill cavity 

 was to be seen rising and falling with a regular 

 pulsating motion, as the animal in breathing took 

 in the water, but which was afterwards ^xjDelled 

 through the siphon. The tentacle-like arms con- 

 trast strongly with those of most other Cepha- 

 lopods, because of their relatively extreme slight- 

 ness and shortness, though they are not shorter 

 proportionally than those of the living Sepia. They 

 are held by the animal whilst swimming extended 

 radially from the head, somewhat like the tentacles 

 in a sea anemone ; but each pair has its definite 

 and different direction, which is constantly main- 

 tained. This direction of the many pairs of ten- 

 tacles at constant but different angles is the most 

 striking feature to be observed in the living 

 Nautilus. Thus, one pair of tentacles was held 

 pointing directly downwards ; two other pairs, 

 situated just before and behind the eyes, were 

 held projecting obliquely outwards and forwards. 



