NATURAL HISTORY. 



CROSS SECTION' OF AKM OF 



OCTOPUS. 



(For explanation of letters see 

 text.) 



connecting the arms. Like other Cephalopocis, however, rapid locomotion is performed stern-foremost 

 by the discharge of water backwards from the funnel. 



The feet or tentacula appended to the head are by no means exclusively destined to effect loco- 

 motion ; they are used, if required, as agents in seizing prey, and of so terrible a character are they, 

 that, armed with these formidable organs, the "Poulpe" becomes one of the most destructive inhabitants 

 of the sea ; for neither superior strength nor activity, nor even defensive 

 armour, is sufficient to save its victims from the ruthless ferocity of such a 

 foe. A hundred and twenty pairs of suckers, more perfect and efficacious 

 than the cupping-glasses of human contrivance, crowd the lower surface of 

 every one of the eight flexible arms. If the Ponlpe but touch its prey, it 

 is enough ; once a few of these tenacious suckers get firm hold, the swiftness 

 of the fish is unavailing, as it is soon trammelled on all sides by the firmly 

 holding tentacula, and dragged to the mouth of its destroyer. The shell of 

 the lobster or crab is a vain protection, for the hard and crooked beak of 

 the Cephalopod easily breaks to pieces the frail armour. (Ryiner Jones.) 



Professor Owen thus describes the tentacles of the Poulpe, or Octopus : 

 " Each arm is perforated near the centre of its axis for the lodgment of its 

 nerve (a, see woodcut) and artery (b) : and upon making a transverse section of 

 the arm, these are seen to be lodged in a quadrangular or rhomboidal space (c) 

 of a light colour and apparently soft homogeneous texture, but in which a few radiating fibres may be 

 discerned. This part is surrounded by four groups of transverse striae, forming as many segments of a 

 circle, external to which there are two thin circular strata of fibres. On making a longitudinal 

 section of the part, the striated segments are seen to consist of longitudinal muscular fibres, and of the 

 surrounding strata, the fibres of the internal are longitudinal, and those of the external transverse. 

 It is easy to conceive that, like the tongue in Mammalia, the arms thus organised may be lengthened, 

 shortened, curved, and bent in all conceivable directions. 



" The acetabula or suckers with which the internal surface of the arms of the Dibranchiates is 

 provided, vary in relative position, in size, in structure, and in mode of attachment, not only in 

 different species, but in different arms in the same individual, and sometimes 

 in different parts of the same arm. Thus, in Loligopsis veranii, the suckers 

 on the long cylindrical stem are sessile, while those on the expanded 

 extremity are supported on long peduncles ; and there is a remark- 

 able instance of suckers having different structure for different functions 

 in the same arm. In the Dibranchiate genera, which are charac- 

 terised by a soft thin skin, as the Argonaut, Octopus, and Eledone, the 

 suckers are soft and unarmed ; in those genera which have a hard thick 

 skin, as the Calamary and Onychoteuthis, hooks are developed in the cavities 

 of the suckers." 



" The circumference of the disc," says Dr. Roget, " is raised by a soft and 

 tumid margin ; a series of long slender folds of membrane, covering cor- 

 responding fasciculi of muscular fibres, converge from the circumference 

 towards the centre of the sucker, at a short distance from which they leave 

 a circular aperture. This opens into a cavity which widens as it descends, 

 and contains a cone of soft substance rising from the bottom of the cavity, 



like the piston of a syringe. When the sucker is applied to a surface for the purpose of adhesion, 

 the piston, having previously been raised so as to fill the cavity, is retracted, and a vacuum produced, 

 which may be still further increased by the retraction of the plicated central portion of the disc. So 

 pei-fect is the mechanism for effecting this mode of adhesion, that in the living Cephalopoda, while the 

 muscular fibres continue contracted, it is easier to tear away the substance of the limb than to release 

 it from its attachments : and even in dead animals the suckers retain a considerable power of 

 adhesion." 



The Octopus is crepuscular in its habits, lying concealed in a rock cranny all day, and emerging at 

 dusk in search of prey. Mr. Sylvanus Hanley, the well-known conchologist, who passes every winter 



SVCKERS OF OCTOPUS. 



