212 FAUTTLIJS. 



. sub-quadrate, with a lateral articulation. — Obs. This well known 

 genus, of which there are several species, is named Cimber by 

 Montfort. The shells are brought from India, the Isle of Fance 

 and the Moluccas. Fifteen species are enumerated m. a Mono- 

 graph of the genus by the Author, Thes. Conch. No. 11. Ex. n. 

 EUiptica. See our PI. xv. fig. 323. 



NAUTELLIPSITES. Parkinson. A generic name proposed to 

 include such species of Nautilus as have been compressed, so as 

 to assume an oval instead of a round form. The genus Ellipso- 

 lites of De Montfort consists of species of Ammonites similarly 

 deformed. ■ • 



NAUTILACEA. Bl. The fifth family of Polythalamacea, :B1. 

 the shells of which are described as more or less discoidal, com- 

 pressed, symmetrically convolute ; the last whorl much larger 

 than the others ; which are entirely hidden beneath it and 

 advancing beyond the last but one, so as constantly to form 

 a large oval aperture, which is always, however, modified by 



. the last whorl. The septa are united in the greater number 

 of instances and pierced by- a siphon. This family contains 



. the genera Orbulites, Nautilus, Polystomella and Lenticu- 

 lina. 



NATJTILACEA. Lam. The sixth famHy of Polythalamous 

 Cephalopoda, Lam. contaiuing the genera Discorbites, Sidero- 

 lites, Polystomella, Vorticialis, Nummulites, Nautilus. To 



; these may be added Simplegas and Endosiphonites. Eig. 472 

 to 476. 



NAUTILUS. Auct. {A little boat ^ Fam. NautUacea, Lam. 

 . and Bl. — Descr. Convolute, discoid, chambered, symmetrical ; 

 spire partly or entirely concealed by the last whorl ; aperture 

 modified by the last whorl, wide, sinuated on the dorsal margin ; 

 interior surface pearly ; septa dividing the chambers simple : 

 siphon discontinuous. — Obs. The shell named Nautilus by Pliny 

 is the Argonauta of modern authors, a thin shell, not chambered. 

 The Nautili are known from the Ammonites by the septa being 

 simple, not sinuated as in the latter genus, and in general the 

 volutions of the spire are not visible. Three or four species are 



