11 



Alas, how imagination breaks down by the side of sober facts : 

 many have been the metaphors, much the poetry, 1 written for the 

 last eighteen centuries, all to show how merrily the Nautilus out- 

 spreads his sails to the summer's breeze ; how, when the breeze 

 freshens, he sinks beneath the waves ; how he leads a simple harmless 

 roving life ; — and now we find he walks upon his head, crunches up 

 little crabs, and does not possess a single sail. 



I have thus set forth the two great divisions of the Cephalopoda, 

 as evidenced in the beings of that class inhabiting the present seas. 



The one great group, the Dibranchiata of Owen, being marked 

 (with one exception) by an internal bone or shell, sometimes com- 

 paratively oval and solid as in the Sepia (fig. 1), sometimes thin, 

 slight, and elongated as in the Loligo (fig. 2), sometimes bent 

 evolutely and chambered as in the Spirula, — the animal itself being 

 always furnished with an ink-bag for defence, and two gills for re- 

 spiration. The other and second group (Tetrabranchiata) marked 

 by an external and chambered shell, as in the Pearly Nautilus (fig. 

 3), and by the animal itself being provided with a kind of door to 

 its house, having also four gills for respiration, but destitute of any 

 ink-bag. 



As a note, I ouslit to add that fig. 5. 



the famous Paper Nautilus or Ar- 

 gonaut (fig. 5), seems to exist as an 

 intermediate link between these 

 two groups, the Dibranchiata (two- 

 gilled), and the Tetrabranchiata 

 (four-gilled), having a relation to 

 the first, in that it has two gills and 

 an ink-bag, but connected with the 



, . . . pin Argonauta argo (Paper Nautilus) drawn 



Second, in the possession 01 a Shell, from a specimen preserved in the College 

 .iin.i • i of Sur S eons > represented in its natural 



Which Said shell is also exceptional, position ; on the side of the shell is the 



partially expanded tentacle, erroneously 



from the fact of its consisting only supposed to act as a sail, 

 of one chamber and having no siphuncle. 



Great has been the controversy relating to the creature which in- 



1 E.g. " Learn of the little Nautilus to sail, 



Spread the thin oar, and catch the driving gale." — PorE. 



