a. Octopus cocco =Atlantic warty octopus (Scaeurgus unicirrhus)
b.,c. Octopus tuberculatus = common octopus (Octopus vulgaris)

Octopus
Date 1851
Source http://www.flickr.com/photos/biodivlibrary/6263520689
Author Jean Baptiste Vérany
Full title Mollusques méditeranéens [!]; observés, décrits, figurés, et chromolithographiés d'après le vivant ...
Source: https://commons.wikimedia.org/wiki/File:Mollusques_m%C3%A9diteran%C3%A9ens_(!)_(6263520689).jpg

Atlantic Warty Octopus or Unihorn Octopus - Scaeurgus unicirrhus (Chiaie, 1839-41 in Férussac and D'Orbigny, 1834-1848)

The common octopus (Octopus vulgaris) is a mollusc belonging to the faimily Octopodidae. Octopus vulgaris is found in the eastern Atlantic extends from the Mediterranean Sea and the southern coast of England to at least Senegal in Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic.