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OCTOPODIDAE 485
Family ARGONAUTIDAE
Genus Argonauta Linne 1758
Pelagic octopods in which the dorsal arms of the female are broadly-
expanded into glandular membranes that secrete and hold a delicate, cal-
careous shell for containing the eggs. The males are considerably smaller
than the females, do not have a shell, and the third right arm is modified into
a detachable copulatory organ which persists separately for a certain length
of time in the mantle cavity of the female.
Argonauta argo Linne Common Paper Nautilus
Worldwide in warm waters.
Plates ic; 26y
4 to 8 inches in length, quite fragile, laterally compressed with a narrow
keel, numerous sharp nodules which in the early part of the shell are stained
with dark purplish brown. Rest of shell opaque, milky-white. Occasionally
washed ashore. A. americana Dall is the same.
Argonauta hians Solander Brown Paper Nautilus
Worldwide in warm waters.
Figure gpe, f
Similar to A. argo, but smaller, much "fatter" with a rapidly broadening
keel that bears larger and fewer nodules. Color brownish white with darker
stains on the early part of the keel. Uncommonly washed ashore.
Family TREMOCTOPODIDAE
Genus Tremoctopus Delle Chiaje 1829
Tremoctopus violaceus Delle Chiaje Common Umbrella Octopus
Pelagic in warm waters. Worldwide.
Total length, including the arms, 3 to 6 feet. Deep purplish red in color.
Characterized by the long skin webs between the four dorsal arms, and the
two large holes in the body near the base of the third arm and in front of
the eyes. The species is gregarious, and is occasionally washed ashore on the
east coast of Florida.
Family OCTOPODIDAE
Genus Octopus Lamarck 1798
There are only five valid species of littoral Octopus so far recorded
along the Atlantic Coast. There are a few deep water ones, some of which