00 MANUAL OF THE MOLLUSCA. 



for having taking in ail their tentacles, they upset theii- boat, and so return to 

 the bottom." 



Fig. 44. Nautilus expanded.* 



Distr., 2 or 4 sp. Chinese seas, Indian ocean, Persian gnlf. 



Fossil, about 100 sp. In all strata, S. and N. America (Chile) Europe, 

 India (Pondicherry) . 



Siih-genus. Atv.ria (Bronn), = Megasiphouia D'Orb. 



Tijpc, N. zic-zac Sby. PL II., fig. 12, London clay, Highgate. 



Shelly sutures, "uith a deep lateral lobe ; siphuncle neaily interna], large, 

 continuous, resembling a succession of funnels. 



Fossil, 4 sp. Eocene, N. America, Europe, India. 



Sub-genus ? Discites, McCoy. WJiirls all exposed : the last chamber 

 sometimes produced. L. silmian. — Carb : Hmestoue. 



Temnocheilus, McCoy. Founded on the carinated sp. of the Carb. lime- 

 stone. 



Ol/ptoceras, D'Orb. Pounded on N. dorsalis Phil, and one other species, 

 in which the siphuncle is nearly external. 



* Ideal representation of the nautilus, when expanded, by Professor Loven, who 

 appears to have taken the details from M, Valenciennes memoir in the Archives du 

 Museum, vol. 2, p. 257. h, hood, s, siphon. It is just possible, that when the 

 nautilus issues from its shell, the gas contained in the last, incomplete, air-chamber, 

 may expand ; but this could not happen under any great pressure of water. 



