. The illustrated natural history [microform]. Reptiles; Fishes; Mollusks; Natural history; Reptiles; Poissons; Mollusques; Sciences naturelles. SS. '^^^:-:..-i^>.::£^^^ Viwuiiniria Ifijulinn. ,;,!., ,,MM., (I„ 1, .:,lll,,) ' Sy^u,.,., ,,l.,i,,U,, () m If s * % rernarkable aiip(Mula-(.s liavo hoen l,y soino autliora to the little hooks on tlie calyx ot the woU-kiiown burdock. The central represents a Synnpta in its usual state, and the lowest figure exhibits tiie same creature as it a])i)ears when it is auuoved and is explaining its feelin-v tk simple process
. The illustrated natural history [microform]. Reptiles; Fishes; Mollusks; Natural history; Reptiles; Poissons; Mollusques; Sciences naturelles. SS. '^^^:-:..-i^>.::£^^^ Viwuiiniria Ifijulinn. ,;,!., ,,MM., (I„ 1, .:,lll,,) ' Sy^u,.,., ,,l.,i,,U,, () m If s * % rernarkable aiip(Mula-(.s liavo hoen l,y soino autliora to the little hooks on tlie calyx ot the woU-kiiown burdock. The central represents a Synnpta in its usual state, and the lowest figure exhibits tiie same creature as it a])i)ears when it is auuoved and is explaining its feelin-v tk simple process of cutting itself to pieces. Insutiiciency of food wiu'induce the creature to perlorni tins strange act, and impure water will have the same effect. ^Vk now come to a new and beautiful family of this order, called Echinidffi, because lue covered with spines like the quills of the hedgehog. J'opularly, they are known by tlie name of Sha-ui:chixs, or Sea-ix;gs. i j j In all thase curious beings the upper parts are protected bv a kind of shell always more or less , but extremely variable in form, as will be seen in the following Ihe shell is one oi the most marvellous structures in the animal kin-donr aiHltlie mechanical diOiculties which are overcome in its formation are of no ordinary 111(1. Jn the case oi the common ;, which is shown on the following illus- tmtinii, the shell nearly globular. Now, this shell increases in size with the age •It tlie animal ; and how a hollow sjiherical shell can increase regularly in size not mterially altering its shape, a problem of extreme di(;ulty. It is, however, solved in tlie till lowing manner:— The shell composed of a vast number of separate pieces, wlujse junction is evident «lien he interior of the shell is examined, but is almost entirely hidden by the projections upon the outer surface. These pieces are oi a hexagonal or pentagonal shape, with a slight curve, and hav
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Keywords: ., bookcentury1800, booksubj, booksubjectfishes, booksubjectmollusks
