238 EXTENT OF THE GENUS NAUTILUS. 



I must enter at some length into the natural history of 

 these shells, because the conclusions to which I have been 

 led, by a long and careful investigation of fossil species, are 

 at variance with those of Cuvier and Lamarck, as to the 

 fact of Ammonites being external shells, and also with the 

 prevailing opinions as to the action of the siphon and air 

 chambers, both in Ammonites and Nautili. 



Mechanical Contrivances in the JVautilus. 



The Nautilus not only exists at present in our tropical 

 seas, but is one of those genera which occur in a fossil state 

 in formations of every age ; and the molluscous inhabitants 

 of these shells, having been among the earliest occupants 

 of the ancient deep, have maintained their place through all 

 the changes that the tenants of the ocean have undergone. 



The recent publication of Mr. R. Owen's excellent Me- 

 moir on the Pearly Nautilus, (Nautilus PompiUus Lin.) 1832, 

 affords the first scientific description ever given of the ani- 

 mal by which this long-known shell is constructed.* This 

 Memoir is therefore of high importance, in its relation to 



ther the Sepia found within this shell be really the constructor of it, or a 

 parasitic intruder into a shell formed by some other animal not yet discovered. 

 Mr. Broderip, Mr. Gray, and Mr. G. Sowerby, are of opinion, that this shell 

 is constructed by an animal allied to Carinaria. 



* It is a curious fact, that although the shells of the Nautilus have been 

 familiar to naturalists, from the days of Aristotle, and abound in every col- 

 lection, the only authentic account of the animals inhabiting them, is that by 

 Rumphius, in his history of Amboyna, accompanied by an engraving, 

 which though tolerably correct, as far as it goes, is yet so deficient in detail 

 that it is impossible to learn any thing' from it respecting the internal organ- 

 ization of the animal. 



I rejoice in the present opportunity of bearing testimony to the value of 

 Mr. Owen's higiily philosophical and most admirable memoir upon tiiis sub- 

 ject; a work not less creditable to the author, than honourable to the Royal 

 College of Surgeons, under v.'hose auspices this publication has been sa 

 handsomely conducted. 



