HEAD-FOOTED MOLLUSCS 



315 



Fig. 180.— Spirula 



exist regarding a supposed marine monster, the Great Sea 

 Serpent, or Kraken. Actual measurements which have been 

 made from time to time of bodies or portions of the bodies of 

 such creatures leave no doubt that a total length of over 50 feet 

 may be attained, the greater part of this, however, being taken 

 up by the long arms. Gigantic Squids of the 

 kind are sometimes cast ashore on the western 

 coasts of Britain among other localities. 



Spirula (Fig. 180) is a small animal in which 

 the shell is spiral and divided into numerous 

 chambers by transverse partitions. It is partly 

 enclosed in folds of the skin. The animal itself 

 is but rarely met with, though its shells are 

 common on Pacific shores and may be seen in 

 most museums. 



The Octopods, or 8-armed Cephalopods, differ 

 from the Cuttle- Fishes and Squids in the absence 

 of the two long arms, besides which they are 

 entirely devoid of an internal shell. The visceral 

 hump is short and rounded, and the suckers on the arms are 

 unstalked. The group includes the Octopi and their allies, and 

 the Paper Nautilus or Argonaut. 



The Common Octopus (Octopus vulgaris) is common on 

 rocky shores on the margins of both Atlantic and Mediterranean, 

 lurking in crevices, crawling by means of its sucker -studded 

 arms, or swimming swiftly backwards like the Squids. Each 

 arm is provided with two rows of suckers, while in an Octopod, 

 common on British coasts, Eledone moschata, there is only one. 

 The specific name of this particular species, which is eaten by 

 the Italians, has reference to the strong musky odour of the 

 animal. 



Some Octopods attain a very large size, though they are 

 inferior to Squids in this respect. Large specimens are reputed 

 to be common on the shores of the island of Sark in the 

 Channel group, and a well-known description of an imaginary 

 combat with one of these is given in Victor Hugo's Toilers of 

 the Sea. 



The Argonaut or Paper Nautilus {Argonauta argo) is a pelagic 

 form, common in the Mediterranean, in which the female is pro- 

 vided with a thin cap-shaped shell, which is symmetrical, and 



