23 



the same author sufficient to state that the animal " makes his way along 

 the sand with a moderate degree of rapidity, with his house above him; and 

 though in general dwelling in the deep, has the power of rising and floating 

 on the surface."* And M. Valenciennes considers that its motion in swim- 

 ming may be attributed to the same force as that ascribed by M. Rang to 

 the Argonaut ; namely the injection and ejection of water in and out of the 

 branchial cavity.f It now only remains to be ascertained whether the dif- 

 ferent mutations of pressure which the Nautilus must have to sustain in its 

 passage through the element, are not counteracted by the alternate production 

 of vacua and introduction of water in the chambers of the shell. Certain 

 it is that the Nautilus in its floating position has neither arms capable of 

 rowing nor membranes adapted for sailing, as so prettily described by a 

 poetical philosopher of the present day. J 



Nautilus Pompilius. Plate C. — Lower figure, lateral view of the shell. 

 Upper figure, lateral section of the shell showing the chambers, siphon, 

 and full extent of the animal ; a, the funnel ; b, the tentacles ; c, the 

 hood ; d, the hind fold of the mantle. Reduced from Professor Owen's 

 figure of the specimen captured by Mr. Bennett in Marekini Bay. 



Species. 

 1. Pompilius, Linn. 2. scrobiculator, Grray. 2. umbilicatus, Linn. 



* " In whatever degree the shell is developed in the Cephalopodous Mollusks, we find it in- 

 variably characterized by the symmetry so peculiar to the disposition aud general form of their 

 soft parts : but the extent to which the Pearly Nautilus is covered by its shell, and its close 

 attachment to it, indicated the affinity to the Gasteropods in too strong a manner to escape the 

 penetration of Aristotle, 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." 



" Respecting the economy of the fossil 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 influ- 

 enced only by the re-action of the respiratory currents when expelled by the funnel upon the 

 surrounding medium ; aud at all events it cau no longer be supposed to have been aided by the 

 fabled sails and oars of the Argonaut." — Owen, Memoir on the Pearly Nautilus, p. 52-3. 



f II nage avec facilite dans le sein des eaux en faisant sortir avec force la grand quantite d'eau 

 contenue dans sa cavite branchiale. — Valenciennes, Archives du Museum d'Hist. Nat., 1839. 



% " The Nautilus and the Ammonite And each could swim on the ocean's brim, 



Were launched in storm and strife ; And auon, its sails could furl ; 



Each sent to float, in its tiny boat, And sink to sleep in the great sea deep, 



On the wild, wild sea of life. In a palace all of pearl." 



Kichakdson ; Sketches in Prose and Verse. 



Erratum. In speaking of the geographical distribution of the Argonaut at p. 15, it is described as being confined, as far as 

 we know at present, to the old world. Mr. Cuming has since informed me that he has received specimens of that genus from 

 Valparaiso, Bahia, and Panama, as well as from Curacao, one of the Caribbean Islands. 



