53 



who directly compares it in this respect to a snail ; and the general resemblance 

 must be sufficiently striking when, with his house above him and in the supine 

 position, he makes his way along the sand with a moderate degree of rapidity*. 



After meeting with so many unexpected modifications of structure referable to 

 the inferior groups of Mollusks in the inhabitant of this recent chambered shell, 

 it is natural to suppose that the series of affinities which it tends to illustrate 

 would be rendered still more complete in the organizations of the numerous 

 genera, whose testaceous remains are now only known in a fossil state. 



Respecting the economy of these genera, we may infer from Nautilus that 

 they were chiefly confined by the limitation of their locomotive faculties to 

 creeping at the bottom of the sea, and that one of the offices assigned to them 

 in the scheme of nature was to restrain within due limits the crustaceous and 

 testaceous tribes around them. Granting them, indeed, the power of rising and 

 floating on the surface, yet their navigation was in all probability of a passive 

 kind, or influenced only by the reaction of the respiratory currents when ex- 

 pelled by the funnel upon the surrounding medium ; and at all events it can no 

 longer be supposed to have been aided by the fabled sails and oars of the Ar- 

 gonaut. 



With respect to the position of the fossil-chambered shells in the natural 

 system, it is obvious that little alteration can result from the present examination 

 of Nautilus, and that, therefore, they will continue to occupy the confines of 

 the Cephalopodous class. 



NaturaHsts of the first rank have already selected from among these remains 

 those forms of shell which, approaching nearest to that of Nautilus, may be sup- 

 posed to have been secreted by a similarly organized animal. Professor de Blain- 



* The testimony of Rumpliius on this head is so explicit and circumstantial, that I am induced to 

 quote the passage at length. " When he thus floats on the water, he puts out his head and all his 

 barbs (tentacles), and spreads them upon the water, with the poop (of the shell) above water; but at 

 the bottom he creeps in the reverse position, with his boat above him, and with liis head and barbs 

 upon the ground, making a tolerably quick progress. He keeps himself chiefly upon the ground, 

 creeping sometimes also into the nets of the fishermen : but after a storm, as the weather becomes 

 calm, they are seen in troops floating on the water, being driven up by the agitation of the waves. 

 Whence one may infer, that they congregate in troops at the bottom. This sailing, however, is not 

 of long continuance ; for having taken in all their tentacles, they upset their boat, and so return to 

 the bottom." — D'Amboinische Rariteit-kamer, p. 61. fol. Amsterdam, 1741. 



