XX 



PRELIMINARY OBSERVATIONS. 



called chambered shells, from their being divided by partitions into 

 numerous narrow cells or chambers. A tube, called a siphunculus, 

 passess through the series of chambers. In all probability, ihis tube 

 enabled the animal to rise from great depths of the ocean to the sur- 

 face, by exhausting the water from the chambers, and filling them 

 with air. 



Till within the last few years, these chambered shells have been 

 considered as the habitation of marine animals, like the bivalve and 

 univalve shells ; but a little reflection may convince us, that the cham- 

 bers were much too small to contain the animal, nor could the ani- 

 mal possibly pass from one chamber to another. There is, however, 

 one living species, in which the outward cell or chamber is so much 

 larger than the rest, that there is sufficient space to contain a great part 

 of the animal. This is the nautilus pompilius, an inhabitant of the In- 

 dian Ocean. (See Plate VIII., fig. 3., which represents the animal 

 collapsed in the last, or open chamber of the shell.) 



The animals belonging to the different chambered shells were mol- 

 luscous. (See Chap. II.) They are called by Guvier Cephalopodes, 

 because the organs of motion are placed round the head, and they 

 walk with their heads downwards. The living species of cephalo- 

 podes are for the most part without any external shell ; but some 

 have an internal hard substance without chambers, of which the cut- 

 tle-fish bone aflbrds a familiar example. This is taken out of the body 

 or sac of the animal — the sepia officinalis, which is common on our 

 coasts. 



The general character of the cephalopodes, as given by Cuvier in 

 his Regne Animal, tom. iii., is, "that the mantle or cloak is united 

 under the body of the animal, and forms a muscular sac, which en- 

 velopes all the viscera. The head projects from the opening of the 

 sac; it is round, and has two large eyes, and is surrounded (couron- 

 nee) by fleshy arms or feet, which are conical, and vary in length in 

 difierent species. These arms bend in every direction, and are ex- 

 ceedingly powerful. On the surface of these arms are numerous suck- 

 ers, by which the animal fixes itself strongly to the bodies that it seiz- 

 es and enfolds. These arms serve the animal bcth to seize its prey, 

 to walk, or to swim. It walks in every direction, having the head be- 

 low, and the body above. At the base of the arms isHhe mouth, which 

 is provided with two strong jaws resembling the beak of a parrot, and 

 also with a fleshy gizzard like that of a bird. 



" Most of these animals, when pursued, excrete a particular black 

 liquor, which darkens the water, and conceals them from their ene- 

 mies. Their is a fleshy funnel placed near the neck, which serves 

 the animal for its excretions, and also to eject the water that it ab- 

 sorbs for the purpose of respiration. They are of two sexes, and are 

 voracious and cruel : as they have great agility in seizing their prey, 

 they destroy multitudes of fish and crustaceous animals." The fleshy 

 funnel, or excreting organ, is not seen in fig. 1., being placed on the 

 underside; but in fig. .3., the projecting organ below the tentacula 

 is the funnel. The sepia has the power of contracting its arms; and 

 in some species the arms are much shorter than represented in the 

 plate, fig. 1., but these have, besides, two extremely long arms or 

 feelers. If the accounts of voyagers could be relied upon, there are 

 sepia in the Indian Ocean with arms nine fathoms in length, and so 



