ANIMALS. 219 
chamber the-largest, and containing the animal: siphon central, or marginal and 
internal.” (Owen.’) 
This is the only known Permian Tetrabranchiate family. 
Genus WVautilus, Linneeus. 
Diagnosis.—“ Shell discoid, spiral, multilocular, with simple walls. Whor/s con- 
tiguous, the last whorl enveloping the others. Chambers numerous, formed by 
transverse partitions, which are concave towards the side facing the aperture: they 
are perforated by a tube, and their edges are simple.”” (Lamarck.) 
This is the longest-lived genus of testaceous Cephalopods. It has existed from 
the earliest organic age to the present time,—seeming to be scarce in species 
during one period, and numerous in another: at present, it is represented only by the 
three species, Vautilus Pompilius, N. umbilicatus and NV. virgatus,—which are confined 
to the Southern Ocean.’ 
NAUTILUS FREIESLEBENT, Geimitz. Plate XVII, figs. 13, 14, 15, 16, 20. 
(?) AmmonitEs,* Sedgwick. Trans. Geol. Soc. Lond., 2d series, vol. ii, p. 118, 1829. 
(?) — 4 Proceedings of the Geological Society, vol. i, p. 204. 
NavTILus 5 Phillips, Lardner’s Cyclop., Geology, vol. i, p. 190, 1837. 
—_— FREIESLEBENI, Geinitz. Neues Jahrbuch, p. 637, pl. xi, fig. 1, 1841. 
— —_ sf Gzea von Sachsen, p. 95, 1843. 
ca — a De Verneuil, Bull. Soc. Géol. de France, 2™° serie, 
vol. i, p. 36, 1844. 
(?) AmmonirEs (?) Sedgwick. Op. cit. 
— 35 Geol. Russ., vol. i, p. 226, 1845. 
NavuriLus FREIESLEBENI, Geinitz. Op. cit. 
— — Ps King, Catalogue, p. 14, 1848. 
— — Howse, Trans. T. N. F. C., vol. i, p. 237, 1848. 
— — Ke Versteinerungen, p. 6, pl. i, fig. 7 a, 6, c, 1848. 
Diagnosis. Whorls slightly increasing in size; with a broad flatly-rounded back ; 
marked with delicate incremental strie. Septa slightly simuated at the sides. 
Aperture somewhat squared, having the greatest diameter from side to side. Stphonal 
sheath situated in the inner third of the septa.’ 
! Cyclopedia of Anatomy, loc. cit. 
* Animaux sans Vertebres. The following is the diagnosis published by Linneus: “Testa univalvis, 
isthmus perforata concamerata, polythalamia.” 
3 For a description of the animal of Nautilus, see Professor Owen’s ‘Memoir on the Pearly Nautilus ;’ 
‘ Lectures on Comparative Anatomy,’ vol. i; and the article ‘ Cephalopoda,’ in the ‘ Cyclopzedia of Anatomy,’ 
vol. 1. : 
4 Vide APPENDIX. 
° «Die Stirke der Windungen nimmt nicht bedeutend zu, der Riicken ist breit gerundet, die Kammer- 
scheidewande bilden an den Seiten einen sehr schwachen Sinus. Die Miindung ist etwas hoher als ein an 
