CONCLUDING REMARKS

"It is clear that adult shells of Nautilus may float for considerable periods after death" (House 1987, p.62). With this statement by one of the foremost cephalopod specialists of our time in hand, the reader will possibly wonder what I am hoping to gain by going over some of the same ground again. The reason is simple, namely, that despite the firmly documented status of our knowledge of the post-mortem fate of chambered shells, unsupported opinions to the contrary continue to appear presumably owing to unfamiliarity with the classical literature. House (1987), in his summarizing comments respecting maximum flotation times for shells of species of Nautilus, cites a record by Ishii made in 1981 of an example of a flotation period of 11 years for a tagged specimen. House attempted to explain the disjunct distributional pattern of N. pompilius by suggesting the possibility that shells from western Australia could be carried by currents to East Africa, alternatively, the continuation of the Borneo-Indonesian current might provide the means of transport of shells to eastern Africa.

The nekroplanktonic transport of shells in shallow epicontinental seas, such as the Saharan Cretaceous-Cenozoic episodes, is obviously seldom a question of first-order palaeobiogeographical significance, nor is the factor of depth-related distribution of the live animal in that environmental setting, owing to the shallowness of epicontinental transgressions. The range of environments in which ammonites were at home seems to have been greater than what pertains for living Nautilus.