REPORT ON THE CEPHALOPODA. 199 



Order 11. TETRABRANCHI ATA, Owen. 



Family XXIL Nautilid^. 



Nautilus, Linne, 

 Nautilus pompilius, Linne. 



■ 1758. Nautilus pompilius, Linn., Syet. nat, ed. x. p. 709 ; No. 283, 233. 

 1868. „ „ Kiister, Conch. Cab., sec. 55, p. 9, taf. it. fig. 9. 



Habitat.— ^i&tion 173, off Matuku, Fiji Islands ; June 24, 1874 ; lat. 19° 9' 35" S., 

 long. 179° 41' 50" E. ; 315 fathoms; coral mud. One specimen. 



The specimen of Nautilus pompiliu,s obtained by the Challenger was not in the 

 collection when it came into my hands, so that I can give no further information 

 regarding it than is contained in the following quotation from the Narrative. 



"In dredging off Matuku Island, in 310 and 315 fathoms, on a coral bottom, some 

 Phorus, Turritella, and a few other shells were brought up, as well as numerous 

 specimens of the blind Crustacean, Polycheles, and other animals showing the fauna to 

 be a true deep-water one. 



"A living specimen of the Pearly Nautilus [Nautilus pompilius), so rarely seen in the 

 living condition by any naturalist, was captured here. This was the only specimen of this 

 animal obtained by the dredge or trawl during the voyage. The animal was very lively, 

 though probably not so lively as it would have been if it had been obtained from a less 

 depth, the sudden change of pressure having no doubt very much disarranged its economy. 

 However, it swam round and round a shallow tub in which it was placed, moving after the 

 manner of aU Cephalopods, backwards, that is with the shell foremost. It floated at the 

 surface with a small portion of the top of the shell just out of the water, as observed by 

 Rumphius.^ The shell was maintained with its major plane in a vertical position, and its 

 mouth directed upwards. The animal seemed unable to sink, and the floating of the 

 shell, as described, was due no doubt to some expansion of gas in the interior, occasioned 

 by diminished pressure. The animal moved backwards slowly by a succession of small 

 jerks, the propelling spouts from the siphon being directed somewhat downwards, so that 

 the shell was rotated a little at each stroke, upon its axis, and a slightly greater area of 

 it raised above the surface of the water. Occasionally, when the animal was frightened 

 or touched, it made a sort of dash, by squirting out the water from its siphon with more 

 than usual violence, so as to cause a strong eddy on the surface of the water. On either 

 side of the base of the membranous operculum -like head-fold, which, when the animal is 

 I De Amboinsclie Eariteitkamer, p. 61, Amsterdam, 1705. 



