VI 
INTKODUCTION. 
It will here be useful, for the sake of comparison, to tabulate the 
divisions of the Nautiloids adopted by different palseontologists. 
Quenstedt’s divisions are the following ^ : — 
1. Imperfecti. — Por those in which the whorls are only slightly 
involute. The following species are cited as examples, 
viz. Nautilus ingens, Martin {=N. [SolenocJieilus'] penta- 
gonus, J. Sow.), N. \_Coelonautilus'] canniferus, J. de C. Sow., 
N. [Goelonautilus'] multicar inatus, J. de C. Sow., <fcc. 
2. Moniliferi. — ^With headed siphuncle. Ex. Nautilus [Ttmno- 
cheilus'] hidorsatus, Schloth., N. [Temnoclieilus'] nodosus, 
Munst. 
3. Bisipliites. — For those with an internal (dorsal) lobe. Ex. 
Nautilus aratus, Schl. {^N striatus, J. Sow.). 
4. Bimplices. — For those with smooth or finely striated shells. 
Ex. Nautilus lineatus, J. Sow., N. imperialis, J. Sow., &c. 
5. Undulati. — For those with transverse costae. Ex. Nautilus 
elegans, I. Sow., N. radiatus, J. Sow. 
6. Aganites. — For those with deeply-lobed sutures. Ex. Nautilus 
\ Hercoglossa"\ aganiticus, Schloth., N. \Aturui] Aturi, 
Basterot, &c. 
It will he unnecessary to discuss the relations of these groups, 
which are manifestly of unequal value, further than to say that the 
first {Imjgerfecti) consists of Carboniferous species, and the others 
include the remainder of the Nautilus-]i\.e forms, ranging from the 
Trias to the Eocene. 
D’0rbigny2 proposed the three following divisions for the Nautili 
of the Secondary rocks ; — 
1. Striati. — Composed of species with longitudinal striations in 
the adult. Ex. Nautilus striatus, I. Sow., N. intermedium, 
J. Sow., &c., of the Jurassic. 
2. Badiati. — Composed of species with transverse plications or 
grooves in the adult. Ex. Nautilus plicatus, Fitton, 
N. pseudo-elegans, d’Orb., N. radiatus, J. Sow., N. elegans, 
J. Sow., &c., of the Cretaceous. This group is equal to 
Cymatoceras of Hyatt in part. 
^ Petrefactenkunde Deutschlands, Bd. i. Oepbalopoden, 1846-49, pp. 52-60. 
* Paleontologie Fran 9 aise — Terrains Jurassiques, 1842, tom. i. p. 145. 
® Proc, Boston Soc, Nat, Hist. 1883, vol, xxii. p. 301. 
