PAPER NAUTILUS. 505 



prey, more particularly near the shores ; and fee ' not only on the 

 softer sea-animals, but on the smaller shell-fish. Their mouthy 

 which, as before observed, is situated beneath, is armed with 

 hard and sharp teeth, resembling a kind of spines, and converging 

 towards the centre of the mouth, and differing in number in the 

 different species. We should not omit to observe, that the curious 

 species last mentioned, the Medusa's head star-fish, is chiefly con- 

 fined to the Indian seas, but is sometimes found in those of Europe. 

 Those who may wish for a particular description of the anatomy of 

 the star-fishes, may consult the observations of Reaumur on this 

 subject, published in the Memoirs of the French Academy. 



SECTION V. 



Testaceous Worms, or those possessing Shells. 



We have already seen that these consist of three divisions, accord- 

 ing to the number of valves or pieces of which the entire covering 

 consists ; and hence these divisions are denominated univalves, bi- 

 valves, and multivalves. We shall select a few of the most curiou* 

 instances of each. 



Among the uniyalves, or those possessing only a single shell, 

 the most common perhaps are the snail, (helix,) and the perri-winkie, 

 (turbo,) kinds. Among the most interesting are the paper-nautilus, 

 the pearl-nautilus, and the ship-worm. The animals inhabiting this 

 description of shells, are, for the most part, the slug and the cuttle- 

 fish. 



1. Paper Nautilus. 



Argonauta Argo. Link. 



ft Among the principal miracles of nature," says Pliny, " is the 

 animal called nautilos, or pompilos. It ascends to the surface of 

 the sea in a supine posture, and gradually rising itself up, forces 

 out, by means of its tube, all the water from the shell, hi order that 

 it may swim the more readily ; then throwing back the two fore- 

 most arms, it displays between them a membrane of wonderful te- 

 nuity, which acts as a sail, while with the remaining arms it rows 

 itself along ; the tail in the middle acting as a helm to direct its 



