THE GUIDE TO NATURE 
SHE LEADS IN BEAUTY AND INTEREST j 
ill FROTH. Jj*? 
HOMES TO NATURE'S REALMS. 
EDWARD F. BIGELOW, MANAGING EDITOR! 
, - _ „ 
r i'i J 1 ^ 
Published monthly by The Agassiz Association, ArcAdiA: Sound Beach, Connecticut, 
Subscription, $1.50 a year Single copy, 15 cents 
Entered as Second-Class Matter June 12, 1909, at Sound Beach Post Office, under Act of March 3, 1897. 
Acceptance for mailing at special rate of postage provided for in Section 1103, Act of October 3, 1917, 
authorized on June ' 27 , 1918. 
Volume XIV. AUGUST, 1921 
Number 3 
The Nautili 
By Charles Johnson, Boston Society of Natural History. 
The “Paper Nautilus” ( Argonauta ) 
and the “Pearly Nautilus” (Nautilus ) , 
while belonging to the same class of 
mollusks — Cephalopoda, are very dif- 
ferent creatures and represent two 
widely separated groups. The Nautilus 
secretes a true shell, divided by septa 
into chambers with a central siphuncle. 
The animal has about ninety arms or 
tentacles, arranged in four groups. 
When swimming with the tentacles ex- 
tended radially from the head it re- 
sembles a sea-anemone. 
The Argonauta is closely related to 
the Octopus or Polypus and has eight 
arms. The Argonauta shell is not, 
strictly speaking, a true shell, but a 
shell-like structure confined to the fe- 
male and only partly a secretion of the 
mantle, the greater portion being 
formed by the two expanded or vela- 
mentous arms. Internal partitions are 
lacking and the structure serves as a 
nest for the eggs. The male resembles a 
small octopus, being less than one- 
fourth the size of the female. It was not 
until the middle of the last century that 
the male was accurately described. 
There were also heated discussions as 
to whether the shell was actually made 
by the Argonauta. or whether the polyp 
had not usurped the shell of some 
heteropod mollusk allied to Carinaria. 
It was the two expanded arms referred 
to above that partly secrete and partly 
cover and hold the shell, that were 
taken for sails by the early authors and 
that have made the Argonauta famous 
in both prose and poetry. 
“Learn of the little Nautilus to sail, 
Spread the thin oar and catch the driving 
gale.” (Pope.) 
Some specimens attain a much 
greater size than others and on this ac- 
count have brought large prices. A 
specimen of Argonauta co/npressa Blainv., 
from the Indian Ocean, in the collec- 
tion of the Boston Society of Natural 
History, measures 10 ji inches in its 
greatest diameter. It is said to have 
cost the donor. Col. Thos. H. Perkins, 
$500. (See The Nautilus, vol. 33, p. 
74, 1920.) There is also a very large 
example of Argonauta nodosa Solander, 
in the American Museum of Natural 
History. New York, that measures 87^ 
by 11 inches. 
One species, Argonauta argo var. ameri- 
cana Dali, is frequently found on the 
Florida coast. It is occasionally car- 
ried northward by the Gulf Stream, to 
meet an untimely end in the cold north- 
Copyright 1921 by The Agassiz Association, ArcAdiA: Sound Beach, Conn. 
