NAUTILUS. -215 



Recent species of Nautilus. 



PI. 99, fig. 506 is an ideal view of the animal of Nautilus, with 

 the tentacles expanded. 



The three best known species of the genus Nautilus are N. 

 Pompilius, N. macromphalus and N. umbilicatus. The first 

 species is the most common and has the widest range ; the second 

 species is more limited in its range and rarer ; the third, although 

 found in collections, is scarcer than the two preceding, and has 

 a range peculiar to itself. The range of N. Pomjnlius embraces 

 the islands of the Eastern Archipelago, Erromanga, Aneitum, 

 and other islands of the New Hebrides and also the Feejee group. 

 N. macromphahis is found about the Isle of Pines and New 

 Caledonia ; and the rare N. uinhilicatas in the Solomon Archi- 

 pelago, New Georgia, New Britain, New Ireland, and probably 

 to the eastward of these groups of islands. Dr. Macdonald, of 

 H. M. S. Herald, informs me that on examination and compari- 

 son, there is a marked difference between the tentacula in the 

 first two species. The sculpturing on N. umbilicatus is very dis- 

 tinctly marked on the external surface of the shell, differently 

 from what is observed either in N. Pompilius or N. macrompha- 

 lus, and forming one of its very distinctive characters. The 

 outer edge of the lip of the perfect shell in N. umbilicatus has a 

 narrow, black rim, continuous from the anterior portion of the 

 whorl. In N. Pompilius and N.. macromphalus, the black rim is 

 on the inner side of the edge of the lip. The color of the shells 

 in the different species varies from brick-red and orange of 

 brighter or paler tints, to nearly a dark crimson color, being as 

 various as the colors observed in the common cowrie shells.* 



N. POMPTLTUS, Linn. PL 91). figs. 507, 508. 



Shell sub-orbicular, smooth, imperforate, the umbilicus being 

 covered by a callous deposit. White, flamed transversely with red. 



Polynesia. 



During the voyage of the Challenger, a living N. Pompili/tx 

 was dredged in 320 fathoms, off Matuka Island, Fiji group. It 

 is very lively, swimming around in a tub, in a retrograde 

 action by the ejection of water from the funnel. The tenta- 



Beimett, Proc. Zool. Soc., 226, 1859. 



