SQUIDS, CUTTLE-FISH, AND THEIR ALLIES 159 
should one be cast up on the shore it is broken 
at once by the action of the waves. 
This shell, which is of the coiled type and 
decorated with transverse ridges, is made 
entirely by the female through the agency 
of a secretion she exudes from two large and 
flattened lobes, one of which is situated on the 
end of each of her two longest arms. The 
mantle or outer skin which invests the 
creature’s body, however, also assists in the 
shell-forming process. The argonaut can 
fashion and complete its shell in a very short 
period, and the manner in which she goes to 
work when thus employed is graphically told 
by Professor Holder, who was fortunate enough 
to be able to observe a captive specimen in 
the act of building its home. 
In describing this interesting event, he 
writes: “ Resting upon the bottom of the 
tank, it held its two shell-secreting arms above, 
side by side, in point of fact, they were joined 
at the base. Then from the glands oozed the 
shell-making secretion, and it soon appeared 
as a gelatinous cast of each tentacle, the exact 
size of the shell the animal had been inhabiting. 
The radiations on the face of the tentacles 
made the radiations on the shell, and one 
could imagine that gelatine had been pressed 
into the moulds and allowed to harden. I 
