imperfectly-defined Species of Jurassic Nautili. 279 



the British-Museum Collection measures about 5h inches in 



Fie. 10. 



its greatest diameter 



Nautilus glaber. — a, lateral view, showing; the closed umbilicus and some 

 of the septa exposed by the removal of part of the test ; b, front 

 view, showing; the position of the siph uncle and parts of the sutures 

 where the test is broken. Drawn from a specimen in the British 

 Museum (no. C. 2840). Rather less than half natural size. 



Remarks. This species is nearly related to N. pseudo- 

 lineatus, but differs therefrom in its compressed form, more 

 distant septa, and strongly bent sutures, as well as in the 

 more nearly marginal position of the siphuncle. It has also 

 somewhat close affinities with N. polygonalis, J. de C. Sow- 

 erby *, especially in the curved form of its sutures and the 

 position of its siphuncle. It may be distinguished from that 

 species by its more compressed form, closer septa, and the 

 siphuncle being further removed from the margin. 



Horizon. Inferior Oolite. 



Localities. Somersetshire ; Bayeux (Calvados), France. 



10. Nautilus obesus, J. Sowerby. 



1816. Nautilus obesus, J. Sowerby, Min. Conch, vol. ii. p. 51, pi. exxiv, 

 1832. Nautilus obesus, Lonsdale, Trans. Geol. Soc. ser. ii. vol. iii. p. 273. 

 1834. Nautilus obesus, Robert, Bull. Soc. Geol de France, vol. iv. 



p. 312. 

 1842. Nautilus lineatus, d'Orbigny, Paleoiitologie Franchise, Terr. 



Jurass. vol. i. p. 155, pi. xxxi. (not of J. Sowerby). 



* Min. Conch, vol. vi. p. 56, pi. dxxx. 



