470 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
INTRODUCTION. 
Eledone cirrosa (Lamarck, 1798), or Moschites corrosa, 
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 
Hledone stands to other groups of Cephalopoda :— 
Class CEPHALOPODA. 
1. Sub-class Tetrabranchia, e.g. Nautilus. 
2. Sub-class Dibranchia. 
Order 1. Decapoda, e.g. Sepia. 
Order I1. Octopoda. 
Family Octopodidae—Genus HLEDONE.* 
All Cephalopoda are aquatic marine animals. The 
genus Hledone occurs in the Mediterranean, round the 
Atlantic coasts of Europe, and elsewhere. LHledone 
cirrosa 1s the species confined to British waters, and is the 
only British representative of the genus. To the other 
British genus Octopus, belong O. vulgaris the common 
“ Octopus,” and O. arcticus a smaller deep-sea form. 
Eledone cirrosa has been chosen for this Memoir 
because it 1s 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 /. crrosa 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 Hledone 
cirrosa is Moschites cirrosa. Yet, as the names Octopus and Hledone 
have been in general use for 100 years or more, I think it on the 
whole better to continue to use them, 
