ns 
NAUTILUS. 
parent, flattish, convex on the upper-side, concave and 
deeply perforated underneath, with a slight keel-like ridge: 
spires four, bordered on the outside with a whitish opake 
stripe running spirally to the centre: on the first volution 
are three compartments, nearly at equal distances from 
each other, the lines of junction appearing like white 
curved stripes radiating from the centre, the first of them 
placed distant from tire aperture, which is narrow, some, 
what heart-shaped, and clasping the spire on both sides; 
diameter hardly a quarter of an inch. 
On aquatic plants, v. v . 
3. Nautilus rotatus. Star Nautilus. 
Nautilus Calcar. Montagu , pi. 15. f. 4— Walker, f. 66. 
Shell smooth, equally convex on both sides, rather more 
raised in the middle, with a strong ridge onthe back, which 
is entire : joints six, marked by elevated flexuous lines ra¬ 
diating from the centre like a star, but not quite reaching 
to the outer margin : aperture half heart-shaped, clasping 
the body equally on both sides, furnished with a small per¬ 
foration : minute. 
On shells, corallines, and other substances, v. i\ 
4. Nautilus laevigatulus. Smooth Nautilus . 
Montagu, pi. 18. f. 7, 8— Walker, f. 67- 
Shell smooth, opake, pale rusty-brown, considerably and 
equally convex on both sides, declining to a rounded mar- 
gined edge, but not perfectly forming a keel-like ridge: 
joints about ten, marked by flexuous rather raised lines, 
which emanate from the margin and are rather of a deeper 
color: aperture surrounded by a rim, forming a triangle, 
and not attached to the body : minute. 
In fine and drifted sand. v. rn. 
5. Nautilus depressulus. Depressed Nautilus. 
Montagu, pi. 18. f. 9— Walker, f. 68. 
Shell glossy-white, semitransparent, flat, equal on both 
sides and without any prominent ridge : joints about nine, 
marked by opake curved lines radiating from the centre, 
where there is a small transparent spot, and the curved 
lines 
