Class 1. CEPHALOPODA. 



Animal ; abdominal portion of the hody enveloped in an ample hag- 

 like mantle, at the opening of which is the head with tioo con- 

 spicuous eyes and a pair of horny mandihles, the ivhole being 

 crowned loith arms and tentacles. Branchice two or four in 

 number. Body furnished either with fins or toith a shell. 



Shell ; an involuted spire, open, or chambered. 



The Cephalopods or Head-walking mollusks, so called from their manner 

 of crawHng upon their arms and tentacles with the head downwards, present 

 an interesting hnk of affinity between the vertebrate and invertebrate divi- 

 sions of the Animal Kingdom, between the Fishes on one side, and the oper- 

 culated Gastropods on the other. Like the former, they have an internal 

 cartilaginous skeleton, and by the aid of a caudal and pair of lateral fins, are 

 endowed with great powers of locomotion ; like the latter, they possess the 

 faculty of secreting a testaceous mucus, and, unprovided with fins, obtain 

 their subaqueous powers of flight by the use of a calcareous apparatus con- 

 sisting of an involuted shell. 



The body presents exactly the appearance of an oblong bag crowned with 

 arms and tentacles, provided with a number of suckers, with which they en- 

 lace their prey ; the suckers acting like cupping-glasses. The head at the 

 opening of the bag is furnished with a strong pair of horny mandibles like 

 the beak of a parrot, and on each side is a large conspicuous eye endowed 

 with a strong power of vision. The sexes are separate, and in one species, 

 the Argonaut, the female has the faculty of secreting a light papyraceous 

 sheU for the preservation of her eggs. They are most formidable enemies 

 of the fishes ; their hard beaked mandibles are situated at the summit of 

 the body, and by rising under a fish with their arms and tentacles upper- 

 most, they are enabled to enlace and seize it in a moment. The tentacles in 

 some instances are of immense length, and the animal thows them out Hke 

 a hunting-noose to entangle its prey.* 



We find mention of these remarkable animals in the earliest records of 

 natural history, they were described by Aristotle, and have been the theme 



* "Those alone," says Mr. Owen, "who have witnessed the persevering activity, power, and 

 velocity of motion exercised by the Octopus, when engaged in its destructive practices amongst 

 a shoal of fishes, and who have seen it with its beak buried in the flesh of a victim held fast in 

 the irresistible embrace of its numerous arms, in an instant simultaneously dissolve the attach- 

 ment of its thousand suckers, and disengaging itseK from its prey, dart like an arrow from the 

 net that has been cautiously moved towards it for its capture, can form an adequate idea of the 

 acuteness of visual perception and powers of action witli which this singular and unshapely 

 Cephalopod is endowed." — Trans. Zool. Soc. vol. ii. 1838. 



