CEPHALOPODA. 
47 
which are dilated and specially adapted for this purpose. Only the 
female Argonaut is provided with a shell, the male being shell- 
less and a much smaller creature. The Argonaut-shell is therefore 
not a true shell, but simply a receptacle for the ova, serving at the 
same time for the protection of the parent. 
GMroteuthis Veranyi is remarkable on account of the great length 
Fig. 42. 
GMroteuthis Veranyi (much reduced). 
a, general view of animal; b, magnified view o pedunculated sucker of the 
terminal club of the tentacular arms ; c, internal shell or gladius. 
of the tentacular arms. These are non-retractile and are employed 
to seize their prey when at a distance. 
The species of Octopus are found on the shores of almost all tem- 
perate and tropical seas ; they do not attain to a large size, and are 
without the internal shell or " bone " which is found in the mantle 
of many Cephalopods. That of the Cuttlefish or Sepia (Fig. 43 a) is 
found in abundance on our coasts ; it is composed of numberless 
layers of a friable calcareous substance. That of the Squid tribe is 
of quite another character, consisting of an elongate thin horny 
plate, and strengthened by one or more thickened ribs, in some 
species somewhat resembling a quill-pen. Some species of this pen- 
bearing class related to the Common Squid attain an immense size. 
