NAUTILUS. ARGONAUTA. 145 
with transverse rufous flames gradually ceasing 
towards the lip; diam. 72. W. Nautilus. 13. 1. 
N. UMBILICATULUS. Sub-orbicular, umbili- 
cated on both sides; all the whorls manifested 
within the umbilicus ; sides of the whorls obtusely 
wrinkled; aperture rounded, heart-shaped ; colour 
much resembling the preceding. 6. 
if Vp Uf Fon 
\ | 
ARGONAUTA. 
Shell univalve, unilocular, involute, very thin; spire 
bicarinate, tuberculous, re-entering the aper- 
ture. 
A. ARGO. Large, involute, very thin, white, 
sides transversely ribbed; ribs frequent, forked 
near the keel; carine approximate, tubercular, 
partly blackish red; tubercles small, very nu- 
merous. S. 485. 
H 
