. The popular natural history . Zoology. THE WEBBED SEFIA, 503 is to cover the shell on its exterior, and, as has since been definitely proved, to build up its delicate texture and to repair damages, the substance ot the sheii being secreted bythese arms, and by their broad expansions moulded into shape. I'he modes of progression employed by the Argonaut are to the full as wondrous as its fabied hauits of sailing. lis progression by crawling has already been casually mentioned. While thus engaged, the creature turns itself so as to rest on its head, withdraws its body as tar as possible into i
. The popular natural history . Zoology. THE WEBBED SEFIA, 503 is to cover the shell on its exterior, and, as has since been definitely proved, to build up its delicate texture and to repair damages, the substance ot the sheii being secreted bythese arms, and by their broad expansions moulded into shape. I'he modes of progression employed by the Argonaut are to the full as wondrous as its fabied hauits of sailing. lis progression by crawling has already been casually mentioned. While thus engaged, the creature turns itself so as to rest on its head, withdraws its body as tar as possible into its shell, and, using its arms like legs, creeps slowly but securely along the ground, sometimes affixing its discs to stones or projecting points of rocks for the purpose of hauling itself along. When, however, it wishes to attain greater speed, and to pass through the wide waters, it makes use of a totally different principle. As has already been mentioned, the respiration is achieved by the passage of wattr over the double gills or branchiae ; the water, after it has completed its purpose, being ejected through a moderately long tube, technically called the sipnoii. The orifice of the siphon is directed towards the head of the animal, and it is by means of this simple apparatus that the act of progression is effected. When tlie creature desires to dart rapidly through the water, it. WEBBED SEPIA.—[Cirrhotfuthi^ Muneri.) COMMON SEPIA.—{Sepia officinalis.) gathers its six arms in a straight line, so as to afford the slightest possible resistance to the water through which it passes, keeps its related arms stretched tightly over the shell, and then by violently ejecting water from the siphon, drives itself, by the reaction, in the opposite direction. As the various cephalopods are so numerous as to preclude all possibility of figuring and describing each species, we must therefore content ourselves with a typical form of each family and a general account of its members. The
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
