CEPHALOPODA 163 
the rest is free and coiled up. It has no enlargement like that 
of the Tremoctopus (Pl. 1., Fig. 3); the fihform appendage 
proceeds from the smaller extremity, and sometimes remains 
entangled in the coloured cyst near the base of the outer side 
of the Hectocotylus. It has a chain of neryous ganglia in its 
axis. 
It was the nautilus (primus) of Aristotle, who described it as 
floating on the surface of the sea, in fine weather, and holding 
out its sail-shaped arms to the breeze. It does not use its arms 
as sails, but it sometimes uses them as oars when it wishes to 
progress slowly, while floating on the surface of the sea. 
Distribution : 4 species of argonaut are known; they inhabit 
the open sea throughout the warmer parts of the world, and 
are most active during the night. Captain King took several 
from the stomach of a dolphin caught upwards of 600 leagues 
from land. 
Fossil, 2 species, Tertiary. A. hians is found in the sub- 
apennine tertiaries of Piedmont. ‘This species is stall living in 
the Chinese seas, but not in the Mediterranean. 
FAMILY II.—OcToPoDIpZ. 
Arms similar, elongated, united at the base by a web. Shell 
represented by two short styles, encysted in the substance of 
the mantle. (Owen.) 
Ocropus, Cuvier. Poulpe. 
Etymology, octo, eight, pous (poda), feet. 
Synonyms, cistopus. (Gray.) 
Example, O. tuberculatus, Bl., Pl. I., Figs. 1 and 2 (man 
dibles). 
Body oval, warty or cirrose, without fins; arms long, un- 
equal; suckers in two rows; mantle supported in front by the 
branchial septum. 
The octopods are the “‘ polypi” of Homer and Aristotle ; 
they are solitary animals, frequenting rocky shores, and are 
very actiye and voracious; the females oviposit on sea-weeds, 
or in the cayities of empty shells. In the markets of Smyrna 
and Naples, and the bazaars of India, they are regularly ex- 
posed for sale. ‘‘ Although common (at St. Jago) in the pools 
of water left by the retiring tide, they are not very easily caught. 
By means of their long arms and suckers they can drag their 
bodies into yery narrow creyices, and when thus fixed it re- 
