INTRODUCTION. 



Eledone cirrosa (Lamarck, 1798), or Moschites cirrosa, 

 as it should be called according to the rules of the 

 International Zoological Congress, belongs to one of the 

 two genera of British Cephalopoda Octopoda. The 

 following table, showing the classification adopted in 

 Pelseneer's Text Book, illustrates the relation in which 

 Eledone stands to other groups of Cephalopoda : — 



Class Cephalopoda. 



1. Sub-class Tetrabranchia, e.g. Nautilus. 



2. Sab-class Dibranchia. 



Order I. Deeapoda, e.g. Sepia. 

 Order II. Octopoda. 



Family Octopodidae — Genus Eledone.* 



All Cephalopoda are aquatic marine animals. The 

 genus Eledone occurs in the Mediterranean, round the 

 Atlantic coasts of Europe, and elsewhere. Eledone 

 cirrosa is the species confined to British waters, and is the 

 only British representative of the genus. To the other 

 British genus Octopus, belong 0. vulgaris the common 

 " Octopus,'' and 0. arcticus a smaller deep-sea form. 



Eledone cirrosa has been chosen for this Memoir 

 because it is a convenient type for dissection, and may be 

 fairly easily obtained at the Plymouth and Port Erin 

 Biological Stations. It has also a certain economic 

 importance, feeding on crabs and lobsters, and often 

 extracting them from the crab and lobster pots put out 

 by the fishermen. Popularly E. cirrosa is known as " the 



* As shown by Dr. Hoyle (Manchester Memoirs, Vol. XLV, No. 3, 

 1901, the correct generic names for "Octopus" and "Eledone" are' 

 Polypus and Moschites respectively. Hence the true title of Eledone 

 cirrosa is Moschites cirrosa. Yet, as the names Octopus and Eledone 

 have been in general use for 100 years or more, I think it on the 

 whole better to continue to use them. 



