N. Pompilius. The Pompilius Nautilus. Pl. [36], fig. 3.
Species not umbilicated; the back rounded; aperture round and pearly; siphon sub-central; pale yellow, with chestnut streaks and undulations.
N. umbilicatus. The umbilicated Pompilius. Pl. [36], fig. 1.
Species umbilicated, sub-orbicular; pale fawn colour, with chestnut undated transverse clouds.
FAMILY XXII.
Heteropoda. Two genera.
1. Argonauta. The Paper Sailor. Three species.
The shells of this genus are remarkable for their fragility, delicacy, and elegance; they resemble a scroll, ornamented with various canaliculated grooves from the summit to the margin, which is bicarinated. The colour is usually bluish, but the keel is of a darker hue; they vary greatly in size.
Shell navicular, symmetrical, very thin, compressed, bicarinated, sub-involuted longitudinally in the same plane; aperture very large, entire, symmetrical, square in front, slightly modified by the turn of the summit, and provided on each side with an earlike appendage, with thick and smooth edges; lips sharp.
Argonauta argo.
A. tuberculosa.