SPECIES AND RANGE. 745 



Nautilus, shown in the map at the end of this article, appears to have a special interest 

 It is wholly confined to the seas adjoining the islands of the Eastern Archipelago, 

 including in the latter term the East Indies, Philippines, New Guinea and its dependencies, 

 Solomon Islands, New Caledonia, New Hebrides, and Fiji. Its shells have been picked 

 up on the Nicobar Islands, Japan [Dean] and the coast of New South Wales, drifting 

 to these localities which lie outside the range of the living animal. 



It is curious that so far as is known with any certainty it does not occur west of 

 the Strait of Malacca nor east of Fiji. Although it descends to deep water, the single 

 specimen obtained during the Challenger Expedition having been dredged in 320 fathoms', 

 it is not an abyssal form, but rather seems to affect the vicinity of large islands, which 

 perhaps in former ages were united to still larger continental masses. Mr Charles Hedley, 

 who has developed a remarkable theory of a Melanesian plateau, which amongst other 

 connections united New Caledonia to New Zealand (as indicated primarily by the 

 distribution of land-molluscs), in a recent paper says, " It is remarkable how strictly 

 Nautilus observes as its eastern limit the ancient coast line of the Melanesian plateau ^" 



If the generic distribution is interesting, the local range of one of the three recent 

 species, namely N. macromphalus, is still more strange. Although as noted above there is 

 no apparent difference between the animals which construct the shells of N. pompilius and 

 N. macromphalus respectively, yet these species are quite distinct, as is shown not only 

 by the coiling of the shell, which is quite constant in the latter, but also by their 

 geogi-aphical distribution. N. pompilius is never taken in the New Caledonian Group 

 [New Caledonia, Isle of Pines, Loyaltj' Islands], and N. macroinphalus is never taken 

 anywhere else. The species which occurs among the New Hebrides and Fiji Islands 

 is N. pompilius. When we consider the individual abundance of Nautilus wherever 

 a favourable locality is known, the circumscribed limits of the area frequented by 

 N. macromphalus alone are very puzzlmg. On the other hand so far as we can judge 

 from the scanty data which are available, the area of distribution of N. uinbilicatus overlaps 

 that of N. pompilius, and therefore this factor does not contribute to the differentiation of 

 the species, but in this case the animals are quite distinct, N. zimbilicatus, as I have 

 already mentioned, presenting a characteristic areolation of the upper surface of the hood, 

 resembling the pallial investment of Lepidoteuthis grimaldii described by M. Joubin'. 

 The same description applies to both sets of cutaneous structures, rhombohedral scales 

 of cartilaginous consistency and fibrous texture. Of course they have been independently 

 acquired, since they occur in different regions of the body, on the cephalopodium in 

 N. umbilicatus, on the mantle in Lepidoteuthis. 



It follows from what has preceded that the recent species whicii has the widest 

 known range is N. poiupilius, since it occurs in the Philippines, Moluccas, Bismarck 

 Ai'chipelago, Torres Strait, New Hebrides, and Fiji. The other species which can be obtained 

 in abundance is confined to the New Caledonian Archipelago, namely, N. macromphalus. 

 Finally, the third species N. umbilicatus occurs also in Papuan waters, but the animal 



I Moseley, H. N., Noles by a Naturulist on 11. M.S. ChaUeiiiifr. Edition of 1H!)U, p. 2.')(). (First edit. 187!).) 



- Hedley, C, " Descriptions ol new Mollusoa, chietiy from New Caledonia." P. Linn. Soc. .V. ,5. Wale-i, 



1898, Part I., see p. 100. 



' Campagnes Scient. Prince de Monaco, 1900, Cephalopoda, )). 70, PI. xv. tig. 2. 



