MARINE ANIMALS. 33 



ocean, in former periods of the world, was evidently peopled by an extensive class 

 of these animals, and several possessing shells, similar to these "Argonautas." 

 Of these the specimens are chiefly fossil, the ammonites, many of which have 

 been found of an immense size, and there can be little doubt that their habits 

 and interior formation very much resembled that of the Nautilus, the exterior 

 appearance being almost identical. Mr. Thomas Rhymer Jones, in his excellent 

 work, entitled, "A General Outline of the Animal Kingdom," describes the 

 anatomical formation of these animals minutely, but upon this I do not propose 

 to enter, only observing that the, structure is elaborate, and will be found in 

 the above work, well worthy the attention of the curious in such matters^ 

 illustrated as it is by some very beautiful engravings. 



In reference to this subject, it may not be out of place to speak of the 

 bone of the Cuttle-fish, so often picked up by us on the sea-shore — this is 

 what is called the Dorsal plate, and is formed precisely in the same manner 

 as the shell of the Nautilus, namely, one layer being secreted behind 

 another, so that, as I hinted in that case, the age of the animal might be 

 thereby easily determined were we precisely aware of the time taken in secreting 

 one, and supposing the same period occupied in secreting each. When a 

 transverse section is made of this substance, it is found to consist of lamina 

 or layers of a calcareous substance, each being connected and yet divided by 

 an infinite number of spines or minute pillars — a most beautiful object for 

 the microscope; this arrangement readers it, for its bulk, at once tough and 

 light J and this is quite loosely hung in a sac or mantle on the back of the 

 fish or cephalopod, partly to protect and partly to assist its natatory movements. 



Before I conclude I must observe a striking distinction between the shells 

 of these animals, namely, that whereas that of the Pearly Nautilus is so 

 beautifully divided, or chambered, a structure which so easily enables the 

 cephalopod to rise or sink, that of the Argo, or Paper Nautilus, exhibits 

 no such divisions, but the animal inhabits the entire shell; but upon sections 

 being made of the extinct Nautili, the Ammonites, the same series of 

 chambers is exhibited as in the Pearly Nautilus, and hence I look upon 

 that species as identical with those found in a fossil state. As I have said 

 before, although the animal has been so rarely found, my conviction is that 

 they are no less common in reality than the Argo, but inhabit such remote 

 parts or depths of the ocean as to render their capture almost impossible, 

 and that probably they are seldom at the surface, but sport in a moderate 

 medium of the waters, for which the great strength of the shell would likewise 

 the better qualify them, and hence the ejection or imbibing of water would 

 be equally necessary and useful. That the Argo imbibes and ejects the briny 

 fluid on which it sails, M. Sander Rang himself witnessed; but it may likewise 

 be another before unsuggested use of the walls of the chambers found in the 

 shell of the Naidilus pompilius, that they give strength to resist the pressure 

 of the water at great depths, whereas the beautiful Argo sports near the 

 coast, and is besides, by entirely filling the shell with its soft pliant body, 



VOL. III. Y 



