ORTHOCERATITE. LITUITE. 275 



siphon. The base of the shell beyond the last plate presents 

 a sweUing cavity, wherein the body of the animal seems to 

 have been partly contained. 



The Orthoceratites are str»»ight and conical, and bear the 

 same relation to the Nautili which Baculites (see PI. 44, Fig. 

 .5) bear to Ammonites ; the Orthoceratites, with their simple 

 transverse septa, resembhng straight Nautili ; and the Bacu- 

 lites, with a sinuous septa, having the appearance of straight 

 Ammonites. They vary considerably in external figure, 

 and also in size ; some of the largest species exceeding a 

 yard in length, and half a foot in diameter. A single speci- 

 men has been known to contain nearly seventy air-chambers. 

 The body of the animal which required so large a float to 

 balance it, must have greatly exceeded, in all its proportions, 

 the most gigantic of our recent Cephalopods ; and the vast 

 number of Orthoceratites that are occasionally crowded to- 

 gether in a single block of stone, shows ho^l^ abundantly 

 they must have, swarmed in the waters of the early seas. 

 These shells are found in the greatest numbers in blocks of 

 marble, of a dark red colour, from the transition Limestone 

 of Oeland, which some years ago was imported largely to 

 various parts of Europe for architectural purposes.* 



Lituite* 



Together with the Orthoceratite, in the Transition Lime- 

 stone of Oeland, there occurs a cognate genus of Cham- 



f he Lias at Lyme, and another species in Alpine Limestone of the Oolite for- 

 mation, at Halstadt, in the Tyrol. 



* Part of the pavement in Hampton Court Palace, that of the hall of 

 University College, Oxford, and several tombs of the kings of Poland in 

 the cathedral at Cracow, arc formed of this marble, in which many shells 

 of Orthoceratites are discoverable. The largest known species are found 

 in the Carboniferous limestone of Closeburn, in Dumfrieshire, being nearly 

 of the size of a man's thigh. The presence of such gigantic Mollusks 

 seems to indicate a highly exalted temperature, in the then existing cli- 

 mate of these northern regions of Europe. See Sowerby's Min. Con. Pk 

 24&. 



