M. Valenciennes on the Anatomy 0/ Nautilus. 243 



ties, which must be empty, cannot therefore be at all con- 

 nected with each other. Of the function of this sipho, in 

 which, as Rumphius and Owen have observed, vessels are dis- 

 tributed *, I, at present, have formed no opinion. 



"The animals examined by Owen and myself cannot, in 

 my opinion, belong to the same species. Owen says that the 

 beak of his animal is calcareous at the summit and serrated ; 

 mine has a corneous beak as far as the summit, and is per- 

 fectly smooth at the margin. Owen's Nautilus was fished 

 up near Erromanga, one of the Hebrides ; mine in the New 

 Guinea Sea, therefore at a distance of 1000 or 1200 miles from 

 the former. 



" I can now conceive how a Nautilus moves : it effects this 

 by its long and thick arms, which are combined to a kind 

 of foot ; thus they are able to push themselves along under 

 the surface of the ocean, as our Limnecs and Planorbes do 

 in marshes ; yet with this difference, that these are then in 

 an inverted position, so that the brain lies under the oeso- 

 phagus when they move upon the water ; instead of which the 

 Nautilus remains in its natural position upon the water, the 

 brain above the oesophagus. If it can creep along at the 

 bottom of the sea, as Rumphius asserts, this must certainly 

 take place in an inverted position. The Nautilus is therefore 

 formed entirely after the structure of the Cephalopoda, and 

 has nothing in common with the Gasteropodaf; nor has it any- 

 thing in common with Spirula. Of this I possess fragments, 

 w^hich sufficiently prove their resemblance to the Sepia or 

 Loligo by the form of their mantle, and by having only two 

 branchiae. Belemnites are nothing but straight, not convo- 

 luted, spirulae. The aspect of the Nautilus shows moreover 

 that it can possess no operculum, and that the Aptychus, as 

 M. Voltz supposes, cannot be looked upon as an operculum. 

 If the Aptychus is part of an Ammonite, as is highly proba- 

 ble, then this part must either be sought for near the mouth 

 or in the pharynx.^' 



Remarks of Professor J\ MUller, 

 Essential differences do not occur between Owen and Va- 

 lenciennes in the number of tentacula, but only in the expla- 

 nation of these in reference to the organs in the Sepice. Owen 

 looks upon his digitations or tentacular tubes as the arms, and 

 adopts indeed only the nineteen digitations on each side, 



* [The entire siphon was termed an artery by Rumphius, but he nowhere 

 alludes to the small vessels of the siphon, injected and described by Mr, 

 Owen. — Ed.] 



t [The Nautilus possesses, in common with the Gasteropods, the single 

 systemic heart, without the two separate branchial hearts which charac- 

 terize the higher Cephalopoda. — Ed.] 



R2 



