404 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



fancy, be considered by the Chinese as by far the 

 finer and more valuable of the two for ornamental 

 purposes. Though the surface is quite smooth, it 

 could easily be polished to a higher degree, and 

 when suitably framed might be admired even in 

 a Western drawing-room. 



The Orthoceratidce were pre-eminently palaeozoic 

 Cephalopods. Some of them survived into the 

 mesozoic period, but none of their remains are 

 found later than the Trias. They are a sub-family 

 of the Nautilidce, of which only a single well-known 

 species, Nautilus poinpilius, the Pearly Nautilus, and 

 one or two rarer ones, have survived to the present 

 day. The only other Cephalopods extant with an 

 external shell form the genus Argonauta, of which 

 there are some half-dozen species, notably A. argo, 

 the Argonaut or Paper Nautilus, but the shell has 

 only a single chamber, and is quite external to the 

 animal, not being organically connected, but secreted 

 by the webbed appendages of the female, while the 

 male has no shell. 



The Pearly Nautilus (N. poTnpilius) has a true 

 pallial shell, divided by septa, like so many bulk- 

 heads, into chambers, the animal occupying only 

 the first or outside one of the spiral, while the 

 nutrition of the whole is kept up by the vessels of 

 the siphuncle passing through the centre of them 

 all. These unoccupied chambers are supposed to be 

 filled with air or gas, making the shell more buoyant. 

 Only one specimen was got by the Challenger 

 Expedition. It was dredged off Levuka, one of the 

 Fiji Islands, in 315 fathoms, on a coral bottom. 



" The animal was very lively, though probably not 

 so lively as it would have been 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 all Cepha- 

 lopods backwards, that is with the shell foremost. 

 It floated at the surface with a small portion of the 



